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  <xsd:element id="biib_InventoryVariousProgramsGross" name="InventoryVariousProgramsGross" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element id="biib_InvestmentInBiotechnologyCompaniesThatAreDeterminedToBeUnconsolidatedVariableInterestEntities" name="InvestmentInBiotechnologyCompaniesThatAreDeterminedToBeUnconsolidatedVariableInterestEntities" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="biib_InvestmentInVariableInterestEntitiesTextualAbstract" name="InvestmentInVariableInterestEntitiesTextualAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="biib_InvestmentsByThirdPartyInJointVentureAsPerAgreement" name="InvestmentsByThirdPartyInJointVentureAsPerAgreement" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="biib_InvestmentsInVariableInterestEntitiesAbstract" name="InvestmentsInVariableInterestEntitiesAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="biib_JointVentureOwnerShipPercentageByThirdParty" name="JointVentureOwnerShipPercentageByThirdParty" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="biib_LeadprogramsMember" name="LeadprogramsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="biib_MarketStockUnitsMember" name="MarketStockUnitsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="biib_MaximumTermForAccountsReceivable" name="MaximumTermForAccountsReceivable" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="biib_MinimumTermForAccountsReceivable" name="MinimumTermForAccountsReceivable" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="biib_MortgageAndOtherAssetBackedSecuritiesCurrentMember" name="MortgageAndOtherAssetBackedSecuritiesCurrentMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="biib_MortgageAndOtherAssetBackedSecuritiesNonCurrentMember" name="MortgageAndOtherAssetBackedSecuritiesNonCurrentMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="biib_NeurimmuneMember" name="NeurimmuneMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="biib_NeuropathicpainindicationsMember" name="NeuropathicpainindicationsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="biib_Noncontrollinginterestincreasedecreaseother" name="Noncontrollinginterestincreasedecreaseother" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="biib_NotesPayableToFumedicaMember" name="NotesPayableToFumedicaMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="biib_OneBillionMember" name="OneBillionMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="biib_OutLicensedPatentsMember" name="OutLicensedPatentsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="biib_Overnightreverserepurchaseagreementspercentoftotalassets" name="Overnightreverserepurchaseagreementspercentoftotalassets" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="instant" />
  <xsd:element id="biib_PaymentTermsOfAccountsReceivable" name="PaymentTermsOfAccountsReceivable" nillable="true" substitutionGroup="xbrli:item" type="us-types:durationStringItemType" xbrli:periodType="duration" />
  <xsd:element id="biib_PaymentsReturnsAppliedAgainstProductRevenueReservesRelatingToCurrentYear" name="PaymentsReturnsAppliedAgainstProductRevenueReservesRelatingToCurrentYear" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="biib_PaymentsReturnsAppliedAgainstProductRevenueReservesRelatingToPriorYear" name="PaymentsReturnsAppliedAgainstProductRevenueReservesRelatingToPriorYear" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="biib_PlanAssetsForDeferredCompensationFairValueDisclosure" name="PlanAssetsForDeferredCompensationFairValueDisclosure" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element id="biib_PotentialFutureMilestonePaymentsCommitmentToThirdPartyApproximately" name="PotentialFutureMilestonePaymentsCommitmentToThirdPartyApproximately" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="biib_ProposedDisallowanceByTaxAuthoritiesForPaymentForServices" name="ProposedDisallowanceByTaxAuthoritiesForPaymentForServices" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="biib_Purchaseofcommonstock" name="Purchaseofcommonstock" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="biib_ReconciliationOfEquityAttributableToNonControllingInterestsAbstract" name="ReconciliationOfEquityAttributableToNonControllingInterestsAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="biib_ReconciliationOfEquityAttributableToNoncontrollingInterestsTableTextBlock" name="ReconciliationOfEquityAttributableToNoncontrollingInterestsTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element id="biib_ReimbursementLimitStatedInResolution" name="ReimbursementLimitStatedInResolution" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="biib_RemainingPotentialDevelopmentMilestonePaymentsAndRoyaltiesOnCommercialSalesUnderTermsOfCollaborationAgreement" name="RemainingPotentialDevelopmentMilestonePaymentsAndRoyaltiesOnCommercialSalesUnderTermsOfCollaborationAgreement" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="biib_SamsungBiosimilarAgreementMember" name="SamsungBiosimilarAgreementMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="biib_ScheduleOfRestrictedStockUnitGrantsTableTextBlock" name="ScheduleOfRestrictedStockUnitGrantsTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="biib_ScheduleOfStockOptionGrantsAbstract" name="ScheduleOfStockOptionGrantsAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="biib_SeniorNotesSixPointEightSevenFivePercentDueTwentyEighteenMember" name="SeniorNotesSixPointEightSevenFivePercentDueTwentyEighteenMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="biib_ShareBasedCompensationExpenseIncludedInCostsAndExpenses" name="ShareBasedCompensationExpenseIncludedInCostsAndExpenses" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="biib_StockOptionsAndEmployeeStockPurchasePlanMember" name="StockOptionsAndEmployeeStockPurchasePlanMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="biib_StrategicInvestmentPortfolio" name="StrategicInvestmentPortfolio" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="biib_StrategicInvestmentsMember" name="StrategicInvestmentsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="biib_SummaryOfProductRevenueReservesIncludedInConsolidatedBalanceSheetsAbstract" name="SummaryOfProductRevenueReservesIncludedInConsolidatedBalanceSheetsAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="biib_SummaryOfProductRevenueReservesIncludedInConsolidatedBalanceSheetsTableTextBlock" name="SummaryOfProductRevenueReservesIncludedInConsolidatedBalanceSheetsTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="biib_SummaryOfShareBasedCompensationExpenseAssociatedWithDifferentProgramsAbstract" name="SummaryOfShareBasedCompensationExpenseAssociatedWithDifferentProgramsAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="biib_SwedishOrphanBiovitrumMember" name="SwedishOrphanBiovitrumMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="biib_TecfideraMember" name="TecfideraMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="biib_TermOfLease" name="TermOfLease" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="biib_ThreeBillionMember" name="ThreeBillionMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="biib_TimeVestedRestrictedStockUnitsMember" name="TimeVestedRestrictedStockUnitsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="biib_TysabriProductMember" name="TysabriProductMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="biib_UnconsolidatedJointBusiness" name="UnconsolidatedJointBusiness" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="biib_UnrealizedGainLossesOnForeignCurrencyDerivativesNetBeforeTax" name="UnrealizedGainLossesOnForeignCurrencyDerivativesNetBeforeTax" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
</xsd:schema>
