<?xml version="1.0" encoding="us-ascii"?>
<!-- DFIN ActiveDisclosure(SM) XBRL Schema Document - http://www.dfinsolutions.com/ -->
<!-- Creation Date      : 2020-10-29T02:40:08.3775002+00:00 -->
<!-- Version            : 5.0.1.513 -->
<!-- Package ID         : 711d8d7fb4d74a1995c8da59d98a79fd -->
<!-- Copyright (c) 2020 Donnelley Financial Solutions, Inc. All Rights Reserved. -->
<xsd:schema xmlns:nonnum="http://www.xbrl.org/dtr/type/non-numeric" xmlns:dei="http://xbrl.sec.gov/dei/2019-01-31" xmlns:num="http://www.xbrl.org/dtr/type/numeric" xmlns:us-types="http://fasb.org/us-types/2020-01-31" xmlns:stpr="http://xbrl.sec.gov/stpr/2018-01-31" xmlns:srt-types="http://fasb.org/srt-types/2020-01-31" xmlns:sic="http://xbrl.sec.gov/sic/2020-01-31" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:srt="http://fasb.org/srt/2020-01-31" xmlns:us-gaap="http://fasb.org/us-gaap/2020-01-31" xmlns:naics="http://xbrl.sec.gov/naics/2017-01-31" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:country="http://xbrl.sec.gov/country/2020-01-31" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:currency="http://xbrl.sec.gov/currency/2020-01-31" xmlns:alks="http://www.alkermes.com/20200930" xmlns:exch="http://xbrl.sec.gov/exch/2020-01-31" attributeFormDefault="unqualified" elementFormDefault="qualified" targetNamespace="http://www.alkermes.com/20200930" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <xsd:import schemaLocation="http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd" namespace="http://www.xbrl.org/2003/instance" />
  <xsd:import schemaLocation="http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" namespace="http://www.xbrl.org/2003/linkbase" />
  <xsd:import schemaLocation="http://www.xbrl.org/2005/xbrldt-2005.xsd" namespace="http://xbrl.org/2005/xbrldt" />
  <xsd:import schemaLocation="https://xbrl.sec.gov/country/2020/country-2020-01-31.xsd" namespace="http://xbrl.sec.gov/country/2020-01-31" />
  <xsd:import schemaLocation="https://xbrl.sec.gov/currency/2020/currency-2020-01-31.xsd" namespace="http://xbrl.sec.gov/currency/2020-01-31" />
  <xsd:import schemaLocation="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd" namespace="http://xbrl.sec.gov/dei/2019-01-31" />
  <xsd:import schemaLocation="http://www.xbrl.org/dtr/type/nonNumeric-2009-12-16.xsd" namespace="http://www.xbrl.org/dtr/type/non-numeric" />
  <xsd:import schemaLocation="http://www.xbrl.org/dtr/type/numeric-2009-12-16.xsd" namespace="http://www.xbrl.org/dtr/type/numeric" />
  <xsd:import schemaLocation="https://xbrl.sec.gov/exch/2020/exch-2020-01-31.xsd" namespace="http://xbrl.sec.gov/exch/2020-01-31" />
  <xsd:import schemaLocation="http://www.xbrl.org/lrr/arcrole/factExplanatory-2009-12-16.xsd" namespace="http://www.xbrl.org/2009/arcrole/fact-explanatoryFact" />
  <xsd:import schemaLocation="http://www.xbrl.org/lrr/role/negated-2009-12-16.xsd" namespace="http://www.xbrl.org/2009/role/negated" />
  <xsd:import schemaLocation="http://www.xbrl.org/lrr/role/net-2009-12-16.xsd" namespace="http://www.xbrl.org/2009/role/net" />
  <xsd:import schemaLocation="https://xbrl.sec.gov/naics/2017/naics-2017-01-31.xsd" namespace="http://xbrl.sec.gov/naics/2017-01-31" />
  <xsd:import schemaLocation="https://xbrl.sec.gov/sic/2020/sic-2020-01-31.xsd" namespace="http://xbrl.sec.gov/sic/2020-01-31" />
  <xsd:import schemaLocation="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd" namespace="http://fasb.org/srt/2020-01-31" />
  <xsd:import schemaLocation="http://xbrl.fasb.org/srt/2020/elts/srt-roles-2020-01-31.xsd" namespace="http://fasb.org/srt-roles/2020-01-31" />
  <xsd:import schemaLocation="http://xbrl.fasb.org/srt/2020/elts/srt-types-2020-01-31.xsd" namespace="http://fasb.org/srt-types/2020-01-31" />
  <xsd:import schemaLocation="https://xbrl.sec.gov/stpr/2018/stpr-2018-01-31.xsd" namespace="http://xbrl.sec.gov/stpr/2018-01-31" />
  <xsd:import schemaLocation="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd" namespace="http://fasb.org/us-gaap/2020-01-31" />
  <xsd:import schemaLocation="http://xbrl.fasb.org/us-gaap/2020/elts/us-roles-2020-01-31.xsd" namespace="http://fasb.org/us-roles/2020-01-31" />
  <xsd:import schemaLocation="http://xbrl.fasb.org/us-gaap/2020/elts/us-types-2020-01-31.xsd" namespace="http://fasb.org/us-types/2020-01-31" />
  <xsd:annotation>
    <xsd:appinfo>
      <link:roleType id="TemplateLink" roleURI="http://www.alkermes.com/20200930/role/TemplateLink" xmlns:link="http://www.xbrl.org/2003/linkbase">
        <link:definition>00000 - Document - Template Link</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="alks-20200930_cal.xml" xlink:role="http://www.xbrl.org/2003/role/calculationLinkbaseRef" xlink:title="Calculation Links, all" xlink:type="simple" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" />
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="alks-20200930_def.xml" xlink:role="http://www.xbrl.org/2003/role/definitionLinkbaseRef" xlink:title="Definition Links, all" xlink:type="simple" />
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="alks-20200930_lab.xml" xlink:role="http://www.xbrl.org/2003/role/labelLinkbaseRef" xlink:title="Label Links, all" xlink:type="simple" />
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="alks-20200930_pre.xml" xlink:role="http://www.xbrl.org/2003/role/presentationLinkbaseRef" xlink:title="Presentation Links, all" xlink:type="simple" />
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DocumentDocumentAndEntityInformation" id="Role_DocumentDocumentAndEntityInformation">
        <link:definition>100000 - Document - Document and Entity Information</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/StatementCONDENSEDCONSOLIDATEDBALANCESHEETSUnaudited" id="Role_StatementCONDENSEDCONSOLIDATEDBALANCESHEETSUnaudited">
        <link:definition>100010 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS (unaudited)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/StatementCONDENSEDCONSOLIDATEDBALANCESHEETSParentheticalUnaudited" id="Role_StatementCONDENSEDCONSOLIDATEDBALANCESHEETSParentheticalUnaudited">
        <link:definition>100020 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (unaudited)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/StatementCONDENSEDCONSOLIDATEDSTATEMENTSOFOPERATIONSANDCOMPREHENSIVELOSSUnaudited" id="Role_StatementCONDENSEDCONSOLIDATEDSTATEMENTSOFOPERATIONSANDCOMPREHENSIVELOSSUnaudited">
        <link:definition>100030 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (unaudited)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/StatementCONDENSEDCONSOLIDATEDSTATEMENTSOFOPERATIONSANDCOMPREHENSIVELOSSUnauditedParenthetical" id="Role_StatementCONDENSEDCONSOLIDATEDSTATEMENTSOFOPERATIONSANDCOMPREHENSIVELOSSUnauditedParenthetical">
        <link:definition>100040 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (unaudited) (Parenthetical)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/StatementCONDENSEDCONSOLIDATEDSTATEMENTSOFCASHFLOWSUnaudited" id="Role_StatementCONDENSEDCONSOLIDATEDSTATEMENTSOFCASHFLOWSUnaudited">
        <link:definition>100050 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (unaudited)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/StatementCONDENSEDCONSOLIDATEDSTATEMENTSOFSHAREHOLDERSEQUITY" id="Role_StatementCONDENSEDCONSOLIDATEDSTATEMENTSOFSHAREHOLDERSEQUITY">
        <link:definition>100060 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS&apos; EQUITY</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/StatementCONDENSEDCONSOLIDATEDSTATEMENTSOFSHAREHOLDERSEQUITYParenthetical" id="Role_StatementCONDENSEDCONSOLIDATEDSTATEMENTSOFSHAREHOLDERSEQUITYParenthetical">
        <link:definition>100070 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS&apos; EQUITY (Parenthetical)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureTheCompany" id="Role_DisclosureTheCompany">
        <link:definition>100080 - Disclosure - The Company</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureSummaryOfSignificantAccountingPolicies" id="Role_DisclosureSummaryOfSignificantAccountingPolicies">
        <link:definition>100090 - Disclosure - Summary of Significant Accounting Policies</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureRevenueFromContractsWithCustomers" id="Role_DisclosureRevenueFromContractsWithCustomers">
        <link:definition>100100 - Disclosure - Revenue from Contracts with Customers</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureInvestments" id="Role_DisclosureInvestments">
        <link:definition>100110 - Disclosure - Investments</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureFairValue" id="Role_DisclosureFairValue">
        <link:definition>100120 - Disclosure - Fair Value</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureInventory" id="Role_DisclosureInventory">
        <link:definition>100130 - Disclosure - Inventory</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosurePropertyPlantAndEquipment" id="Role_DisclosurePropertyPlantAndEquipment">
        <link:definition>100140 - Disclosure - Property, Plant and Equipment</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureGoodwillAndIntangibleAssets" id="Role_DisclosureGoodwillAndIntangibleAssets">
        <link:definition>100150 - Disclosure - Goodwill and Intangible Assets</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureLeases" id="Role_DisclosureLeases">
        <link:definition>100160 - Disclosure - Leases</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureAccountsPayableAndAccruedExpenses" id="Role_DisclosureAccountsPayableAndAccruedExpenses">
        <link:definition>100170 - Disclosure - Accounts Payable and Accrued Expenses</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureLongTermDebt" id="Role_DisclosureLongTermDebt">
        <link:definition>100180 - Disclosure - Long-term Debt</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureShareBasedCompensation" id="Role_DisclosureShareBasedCompensation">
        <link:definition>100190 - Disclosure - Share-based Compensation</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureLossPerShare" id="Role_DisclosureLossPerShare">
        <link:definition>100200 - Disclosure - Loss Per Share</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureRestructuring" id="Role_DisclosureRestructuring">
        <link:definition>100210 - Disclosure - Restructuring</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureCommitmentsAndContingentLiabilities" id="Role_DisclosureCommitmentsAndContingentLiabilities">
        <link:definition>100220 - Disclosure - Commitments and Contingent Liabilities</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureSummaryOfSignificantAccountingPoliciesPolicies" id="Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies">
        <link:definition>100230 - Disclosure - Summary of Significant Accounting Policies (Policies)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureRevenueFromContractsWithCustomersTables" id="Role_DisclosureRevenueFromContractsWithCustomersTables">
        <link:definition>100240 - Disclosure - Revenue from Contracts with Customers (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureInvestmentsTables" id="Role_DisclosureInvestmentsTables">
        <link:definition>100250 - Disclosure - Investments (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureFairValueTables" id="Role_DisclosureFairValueTables">
        <link:definition>100260 - Disclosure - Fair Value (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureInventoryTables" id="Role_DisclosureInventoryTables">
        <link:definition>100270 - Disclosure - Inventory (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosurePropertyPlantAndEquipmentTables" id="Role_DisclosurePropertyPlantAndEquipmentTables">
        <link:definition>100280 - Disclosure - Property, Plant and Equipment (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsTables" id="Role_DisclosureGoodwillAndIntangibleAssetsTables">
        <link:definition>100290 - Disclosure - Goodwill and Intangible Assets (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureLeasesTables" id="Role_DisclosureLeasesTables">
        <link:definition>100300 - Disclosure - Leases (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureAccountsPayableAndAccruedExpensesTables" id="Role_DisclosureAccountsPayableAndAccruedExpensesTables">
        <link:definition>100310 - Disclosure - Accounts Payable and Accrued Expenses (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureLongTermDebtTables" id="Role_DisclosureLongTermDebtTables">
        <link:definition>100320 - Disclosure - Long-term Debt (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureShareBasedCompensationTables" id="Role_DisclosureShareBasedCompensationTables">
        <link:definition>100330 - Disclosure - Share-based Compensation (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureLossPerShareTables" id="Role_DisclosureLossPerShareTables">
        <link:definition>100340 - Disclosure - Loss Per Share (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureRestructuringTables" id="Role_DisclosureRestructuringTables">
        <link:definition>100350 - Disclosure - Restructuring (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformationDetails" id="Role_DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformationDetails">
        <link:definition>100360 - Disclosure - Summary of Significant Accounting Policies - Additional Information (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureRevenueFromContractsWithCustomersScheduleOfDisaggregationOfRevenueDetails" id="Role_DisclosureRevenueFromContractsWithCustomersScheduleOfDisaggregationOfRevenueDetails">
        <link:definition>100370 - Disclosure - Revenue from Contracts with Customers - Schedule of Disaggregation of Revenue (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureRevenueFromContractsWithCustomersScheduleOfManufacturingAndRoyaltyRevenuesDetails" id="Role_DisclosureRevenueFromContractsWithCustomersScheduleOfManufacturingAndRoyaltyRevenuesDetails">
        <link:definition>100380 - Disclosure - Revenue from Contracts with Customers - Schedule of Manufacturing and Royalty Revenues (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureRevenueFromContractsWithCustomersAdditionalInformationDetails" id="Role_DisclosureRevenueFromContractsWithCustomersAdditionalInformationDetails">
        <link:definition>100390 - Disclosure - Revenue from Contracts with Customers - Additional Information (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureRevenueFromContractsWithCustomersScheduleOfContractAssetsAndContractLiabilitiesDetails" id="Role_DisclosureRevenueFromContractsWithCustomersScheduleOfContractAssetsAndContractLiabilitiesDetails">
        <link:definition>100400 - Disclosure - Revenue from Contracts with Customers - Schedule of Contract Assets and Contract Liabilities (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureInvestmentsScheduleOfInvestmentsDetails" id="Role_DisclosureInvestmentsScheduleOfInvestmentsDetails">
        <link:definition>100410 - Disclosure - Investments - Schedule of Investments (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureInvestmentsAdditionalInformationDetails" id="Role_DisclosureInvestmentsAdditionalInformationDetails">
        <link:definition>100420 - Disclosure - Investments - Additional Information (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureInvestmentsScheduleOfProceedsFromSalesAndMaturitiesOfMarketableSecuritiesPlusResultingRealizedGainsAndLossesDetails" id="Role_DisclosureInvestmentsScheduleOfProceedsFromSalesAndMaturitiesOfMarketableSecuritiesPlusResultingRealizedGainsAndLossesDetails">
        <link:definition>100430 - Disclosure - Investments - Schedule of Proceeds from Sales and Maturities of Marketable Securities Plus Resulting Realized Gains and Losses (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureInvestmentsScheduleOfContractualMaturitiesOfAvailableForSaleAndHeldToMaturitySecuritiesDetails" id="Role_DisclosureInvestmentsScheduleOfContractualMaturitiesOfAvailableForSaleAndHeldToMaturitySecuritiesDetails">
        <link:definition>100440 - Disclosure - Investments - Schedule of Contractual Maturities of Available-for-Sale and Held-to-Maturity Securities (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureFairValueSummaryOfCompanySAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails" id="Role_DisclosureFairValueSummaryOfCompanySAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails">
        <link:definition>100450 - Disclosure - Fair Value - Summary of the Company&apos;s Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureFairValueAdditionalInformationDetails" id="Role_DisclosureFairValueAdditionalInformationDetails">
        <link:definition>100460 - Disclosure - Fair Value - Additional Information (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureFairValueRollforwardOfFairValueOfAssetsDeterminedUsingLevel3InputsDetails" id="Role_DisclosureFairValueRollforwardOfFairValueOfAssetsDeterminedUsingLevel3InputsDetails">
        <link:definition>100470 - Disclosure - Fair Value - Rollforward of the Fair Value of the Assets Determined using Level 3 Inputs (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureInventoryScheduleOfInventoriesDetails" id="Role_DisclosureInventoryScheduleOfInventoriesDetails">
        <link:definition>100480 - Disclosure - Inventory - Schedule of Inventories (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureInventoryScheduleOfInventoriesParentheticalDetails" id="Role_DisclosureInventoryScheduleOfInventoriesParentheticalDetails">
        <link:definition>100490 - Disclosure - Inventory - Schedule of Inventories (Parenthetical) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureInventoryAdditionalInformationDetails" id="Role_DisclosureInventoryAdditionalInformationDetails">
        <link:definition>100500 - Disclosure - Inventory - Additional Information (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosurePropertyPlantAndEquipmentScheduleOfPropertyPlantAndEquipmentDetails" id="Role_DisclosurePropertyPlantAndEquipmentScheduleOfPropertyPlantAndEquipmentDetails">
        <link:definition>100510 - Disclosure - Property, Plant and Equipment - Schedule of Property, Plant and Equipment (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsScheduleOfGoodwillAndIntangibleAssetsDetails" id="Role_DisclosureGoodwillAndIntangibleAssetsScheduleOfGoodwillAndIntangibleAssetsDetails">
        <link:definition>100520 - Disclosure - Goodwill and Intangible Assets - Schedule of Goodwill and Intangible Assets (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsAdditionalInformationDetails" id="Role_DisclosureGoodwillAndIntangibleAssetsAdditionalInformationDetails">
        <link:definition>100530 - Disclosure - Goodwill and Intangible Assets - Additional Information (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureLeasesAdditionalInformationDetails" id="Role_DisclosureLeasesAdditionalInformationDetails">
        <link:definition>100540 - Disclosure - Leases - Additional Information (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureLeasesSummaryOfFutureLeasePaymentsUnderNonCancelableLeasesDetails" id="Role_DisclosureLeasesSummaryOfFutureLeasePaymentsUnderNonCancelableLeasesDetails">
        <link:definition>100550 - Disclosure - Leases - Summary of Future Lease Payments Under Non-Cancelable Leases (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureLeasesSummaryOfFutureLeasePaymentsUnderNonCancelableLeasesDetails2" id="Role_DisclosureLeasesSummaryOfFutureLeasePaymentsUnderNonCancelableLeasesDetails2">
        <link:definition>100560 - Disclosure - Leases - Summary of Future Lease Payments Under Non-Cancelable Leases (Details)2</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureAccountsPayableAndAccruedExpensesScheduleOfAccountsPayableAndAccruedExpensesDetails" id="Role_DisclosureAccountsPayableAndAccruedExpensesScheduleOfAccountsPayableAndAccruedExpensesDetails">
        <link:definition>100570 - Disclosure - Accounts Payable and Accrued Expenses - Schedule of Accounts Payable and Accrued Expenses (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureLongTermDebtScheduleOfLongTermDebtDetails" id="Role_DisclosureLongTermDebtScheduleOfLongTermDebtDetails">
        <link:definition>100580 - Disclosure - Long-term Debt - Schedule of Long-term Debt (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureLongTermDebtAdditionalInformationDetails" id="Role_DisclosureLongTermDebtAdditionalInformationDetails">
        <link:definition>100590 - Disclosure - Long-term Debt - Additional Information (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureShareBasedCompensationScheduleOfShareBasedCompensationExpenseDetails" id="Role_DisclosureShareBasedCompensationScheduleOfShareBasedCompensationExpenseDetails">
        <link:definition>100600 - Disclosure - Share-based Compensation - Schedule of Share-based Compensation Expense (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureShareBasedCompensationAdditionalInformationDetails" id="Role_DisclosureShareBasedCompensationAdditionalInformationDetails">
        <link:definition>100610 - Disclosure - Share-based Compensation - Additional Information (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureLossPerShareScheduleOfAntiDilutivePotentialCommonShareEquivalentExcludedFromCalculationOfLossPerShareDetails" id="Role_DisclosureLossPerShareScheduleOfAntiDilutivePotentialCommonShareEquivalentExcludedFromCalculationOfLossPerShareDetails">
        <link:definition>100620 - Disclosure - Loss Per Share - Schedule of Anti-Dilutive Potential Common Share Equivalent Excluded from Calculation of Loss Per Share (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureRestructuringAdditionalInformationDetails" id="Role_DisclosureRestructuringAdditionalInformationDetails">
        <link:definition>100630 - Disclosure - Restructuring - Additional Information (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureRestructuringScheduleOfRestructuringActivityDetails" id="Role_DisclosureRestructuringScheduleOfRestructuringActivityDetails">
        <link:definition>100640 - Disclosure - Restructuring - Schedule of Restructuring Activity (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.alkermes.com/20200930/taxonomy/role/DisclosureCommitmentsAndContingentLiabilitiesAdditionalInformationDetails" id="Role_DisclosureCommitmentsAndContingentLiabilitiesAdditionalInformationDetails">
        <link:definition>100650 - Disclosure - Commitments and Contingent Liabilities - Additional Information (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
    </xsd:appinfo>
  </xsd:annotation>
  <xsd:element id="alks_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFour" name="LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFour" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="alks_ManufacturedProductAndRoyaltyMember" name="ManufacturedProductAndRoyaltyMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="alks_ResearchAndDevelopmentMember" name="ResearchAndDevelopmentMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="alks_IncreaseDecreaseInRightOfUseAsset" name="IncreaseDecreaseInRightOfUseAsset" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="alks_IncreaseDecreaseInOperatingLeaseLiabilities" name="IncreaseDecreaseInOperatingLeaseLiabilities" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="alks_ProceedsFromContingentConsideration" name="ProceedsFromContingentConsideration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="alks_ReturnOfInvestments" name="ReturnOfInvestments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="alks_ReceiptOfCompanyStockForExerciseOfStockOptionsOrToSatisfyMinimumTaxWithholdingObligationsRelatedToStockBasedAwardsShares" name="ReceiptOfCompanyStockForExerciseOfStockOptionsOrToSatisfyMinimumTaxWithholdingObligationsRelatedToStockBasedAwardsShares" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="alks_ReceiptOfCompanyStockForExerciseOfStockOptionsOrToSatisfyMinimumTaxWithholdingObligationsRelatedToStockBasedAwardsValue" name="ReceiptOfCompanyStockForExerciseOfStockOptionsOrToSatisfyMinimumTaxWithholdingObligationsRelatedToStockBasedAwardsValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="alks_ProceedsAndRealizedGainLossOnMarketableSecuritiesTableTextBlock" name="ProceedsAndRealizedGainLossOnMarketableSecuritiesTableTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="alks_SummaryOfSignificantAccountingPoliciesLineItems" name="SummaryOfSignificantAccountingPoliciesLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="alks_SummaryOfSignificantAccountingPoliciesTable" name="SummaryOfSignificantAccountingPoliciesTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="alks_VivitrolMember" name="VivitrolMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="alks_AristadaMember" name="AristadaMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="alks_PercentageOfIncreaseDecreaseInProductUnitsSoldDueToCOVID19Pandemic" name="PercentageOfIncreaseDecreaseInProductUnitsSoldDueToCOVID19Pandemic" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="alks_AristadaOrAristadaInitioMember" name="AristadaOrAristadaInitioMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="alks_InvegaSustennaOrXeplionAndInvegaTrinzaMember" name="InvegaSustennaOrXeplionAndInvegaTrinzaMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="alks_RISPERDALCONSTAMember" name="RISPERDALCONSTAMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="alks_OtherProductsAndServicesMember" name="OtherProductsAndServicesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="alks_ManufacturingRevenueMember" name="ManufacturingRevenueMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="alks_CollaborativeArrangementAdditionalRevenue" name="CollaborativeArrangementAdditionalRevenue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="alks_BiogenMember" name="BiogenMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="alks_ManufacturingProcessPeriod" name="ManufacturingProcessPeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="alks_ConsiderationExpectsToReceivePeriod" name="ConsiderationExpectsToReceivePeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="alks_ContractWithCustomerAssetAdditions" name="ContractWithCustomerAssetAdditions" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="alks_ContractWithCustomerLiabilityAdditions" name="ContractWithCustomerLiabilityAdditions" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="alks_ShortTermInvestmentAmortizedCost" name="ShortTermInvestmentAmortizedCost" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="alks_ShortTermInvestmentSecuritiesUnrealizedGainLoss" name="ShortTermInvestmentSecuritiesUnrealizedGainLoss" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="alks_ShortTermInvestmentSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses" name="ShortTermInvestmentSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="alks_ShortTermInvestmentSecuritiesContinuousUnrealizedLossPositionMoreThan12MonthsAggregateLosses" name="ShortTermInvestmentSecuritiesContinuousUnrealizedLossPositionMoreThan12MonthsAggregateLosses" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="alks_ShortTermInvestmentSecuritiesAllowanceForCreditLoss" name="ShortTermInvestmentSecuritiesAllowanceForCreditLoss" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="alks_MarketableSecuritiesAtAmortizedCost" name="MarketableSecuritiesAtAmortizedCost" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="alks_MarketableInvestmentsSecuritiesUnrealizedGainLoss" name="MarketableInvestmentsSecuritiesUnrealizedGainLoss" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="alks_MarketableSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses" name="MarketableSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="alks_MarketableSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses" name="MarketableSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="alks_MarketableSecuritiesAllowanceForCreditLoss" name="MarketableSecuritiesAllowanceForCreditLoss" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="alks_LongTermInvestmentAmortizedCost" name="LongTermInvestmentAmortizedCost" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="alks_LongTermInvestmentSecuritiesUnrealizedGainLoss" name="LongTermInvestmentSecuritiesUnrealizedGainLoss" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="alks_LongTermInvestmentSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses" name="LongTermInvestmentSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="alks_LongTermInvestmentSecuritiesContinuousUnrealizedLossPositionMoreThan12MonthsAggregateLosses" name="LongTermInvestmentSecuritiesContinuousUnrealizedLossPositionMoreThan12MonthsAggregateLosses" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="alks_LongTermInvestmentsMember" name="LongTermInvestmentsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="alks_FixedTermDepositAccountMember" name="FixedTermDepositAccountMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="alks_FountainHealthcarePartnersIiLpOfIrelandMember" name="FountainHealthcarePartnersIiLpOfIrelandMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="alks_HeldInEscrowMember" name="HeldInEscrowMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="alks_CommitmentOnEquityMethodInvestments" name="CommitmentOnEquityMethodInvestments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="alks_FundingCommitmentAsPercentageOfPartnershipsFunding" name="FundingCommitmentAsPercentageOfPartnershipsFunding" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="alks_EquityMethodCommitment" name="EquityMethodCommitment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="alks_NumberOfPortfolioSold" name="NumberOfPortfolioSold" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="alks_MarketableSecuritiesRealizedGain" name="MarketableSecuritiesRealizedGain" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="alks_MarketableSecuritiesRealizedLoss" name="MarketableSecuritiesRealizedLoss" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="alks_FairValueRecurringBasisAssetsOrLiabilitiesTransfersBetweenLevels" name="FairValueRecurringBasisAssetsOrLiabilitiesTransfersBetweenLevels" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="alks_TwentyTwentyThreeTermLoansMember" name="TwentyTwentyThreeTermLoansMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="alks_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetImpairmentOfCorporateDebtSecurity" name="FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetImpairmentOfCorporateDebtSecurity" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="alks_FairValueOfContingentConsiderationMember" name="FairValueOfContingentConsiderationMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="alks_MilestonePaymentsReceivable" name="MilestonePaymentsReceivable" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="alks_MilestonePaymentsReceived" name="MilestonePaymentsReceived" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="alks_AdditionalMilestonePaymentsReceived" name="AdditionalMilestonePaymentsReceived" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="alks_InventoryFinishedGoodsNetOfReservesLocatedAtThirdPartyWarehouseAndShippingServiceProvider" name="InventoryFinishedGoodsNetOfReservesLocatedAtThirdPartyWarehouseAndShippingServiceProvider" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="alks_FIFOInventoryAdvanceCapitalizationAmount" name="FIFOInventoryAdvanceCapitalizationAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="alks_FurnitureFixtureAndEquipmentMember" name="FurnitureFixtureAndEquipmentMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="alks_NanoCrystalTechnologyMember" name="NanoCrystalTechnologyMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="alks_OCRTechnologyMember" name="OCRTechnologyMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="alks_OperatingLeaseProvisionForExtensionOfTerm" name="OperatingLeaseProvisionForExtensionOfTerm" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="alks_LeaseAgreementCommencementDate" name="LeaseAgreementCommencementDate" type="xbrli:dateItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="alks_LeaseExpirationYear" name="LeaseExpirationYear" type="xbrli:gYearItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="alks_BasePremisesMember" name="BasePremisesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="alks_AdditionalPremisesMember" name="AdditionalPremisesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="alks_LeaseAgreementCommencementPeriod" name="LeaseAgreementCommencementPeriod" type="xbrli:gYearMonthItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="alks_LeaseExpirationPeriod" name="LeaseExpirationPeriod" type="xbrli:gYearMonthItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="alks_AccruedSalesDiscountsAllowancesAndReserves" name="AccruedSalesDiscountsAllowancesAndReserves" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="alks_DebtInstrumentVariableRateBasisFloor" name="DebtInstrumentVariableRateBasisFloor" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="alks_InventoryMember" name="InventoryMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="alks_PerformanceBasedRestrictedStockUnitsMember" name="PerformanceBasedRestrictedStockUnitsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="alks_RestructuringAndRelatedActivitiesInitiationMonthAndYear" name="RestructuringAndRelatedActivitiesInitiationMonthAndYear" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="alks_PaymentsForRestructuringSeverance" name="PaymentsForRestructuringSeverance" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="alks_PaymentsForRestructuringOutplacementServices" name="PaymentsForRestructuringOutplacementServices" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="alks_PaymentsForRestructuringBenefits" name="PaymentsForRestructuringBenefits" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="alks_MaximumPeriodBeforeFDACanApprovePatentRequest" name="MaximumPeriodBeforeFDACanApprovePatentRequest" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
</xsd:schema>
