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  <xsd:element id="regn_DeferredRevenueFromRelatedPartyCurrent" name="DeferredRevenueFromRelatedPartyCurrent" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="regn_DeferredRevenueFromRelatedPartyNoncurrent" name="DeferredRevenueFromRelatedPartyNoncurrent" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="regn_DistributionRelatedFeesMember" name="DistributionRelatedFeesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_DocumentAndEntityInformationAbstract" name="DocumentAndEntityInformationAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_EyleaNetProductSalesMember" name="EyleaNetProductSalesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_FacilityLeaseObligationsCurrent" name="FacilityLeaseObligationsCurrent" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="regn_FacilityLeaseObligationsNoncurrent" name="FacilityLeaseObligationsNoncurrent" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="regn_Facilityleaseobligationrecognizedduringtheperiod" name="Facilityleaseobligationrecognizedduringtheperiod" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Futuredevelopmentmilestonepayments" name="Futuredevelopmentmilestonepayments" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_GrosssalesrevenueMember" name="GrosssalesrevenueMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_IncrementalCommonSharesAttributableToNonvestedRestrictedShares" name="IncrementalCommonSharesAttributableToNonvestedRestrictedShares" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_InternationalGovernmentObligationsFairValueDisclosure" name="InternationalGovernmentObligationsFairValueDisclosure" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="regn_InternationalgovernmentagencyobligationsMember" name="InternationalgovernmentagencyobligationsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Levelsoftwelvemonthsalesatwhichsalesmilestonepaymentsmaybereceived200million" name="Levelsoftwelvemonthsalesatwhichsalesmilestonepaymentsmaybereceived200million" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="regn_Levelsoftwelvemonthsalesatwhichsalesmilestonepaymentswerereceived" name="Levelsoftwelvemonthsalesatwhichsalesmilestonepaymentswerereceived" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="regn_Levelsoftwelvemonthsalesatwhichsalesmilestonepaymentswerereceived5thtier" name="Levelsoftwelvemonthsalesatwhichsalesmilestonepaymentswerereceived5thtier" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="regn_Levelsoftwelvemonthssalesatwhichsalesmilestonepaymentsmaybereceived1billion" name="Levelsoftwelvemonthssalesatwhichsalesmilestonepaymentsmaybereceived1billion" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_LossContingenciesByGeographicAreaAxis" name="LossContingenciesByGeographicAreaAxis" nillable="true" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_LossContingenciesByGeographicAreaDomain" name="LossContingenciesByGeographicAreaDomain" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_MaximumAmountOfSalesMilestonePaymentsIfTotalSalesAchieveSpecificLevels" name="MaximumAmountOfSalesMilestonePaymentsIfTotalSalesAchieveSpecificLevels" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="regn_Maximumamountofmilestonepaymentsthatmaybereceivedifcertainsalesareachieved" name="Maximumamountofmilestonepaymentsthatmaybereceivedifcertainsalesareachieved" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_MilestonePayment" name="MilestonePayment" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_MunicipalBondsFairValueDisclosure" name="MunicipalBondsFairValueDisclosure" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element id="regn_NetProfitLossFromCommercializationOfProductsUnderCollaborationAgreement" name="NetProfitLossFromCommercializationOfProductsUnderCollaborationAgreement" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="regn_NumberofPaymentstheCompanymade" name="NumberofPaymentstheCompanymade" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_NumberofdevelopmentmilestonepaymentstheCompanyreceived" name="NumberofdevelopmentmilestonepaymentstheCompanyreceived" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_NumberofsalesmilestonepaymentstheCompanyreceived" name="NumberofsalesmilestonepaymentstheCompanyreceived" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Numberoftherapeutictargets" name="Numberoftherapeutictargets" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_NumberoftherapeutictargetsofAvalancheschoice" name="NumberoftherapeutictargetsofAvalancheschoice" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Optinpayment" name="Optinpayment" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_OtherCollaborationRevenue" name="OtherCollaborationRevenue" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_OtherSalesRelatedDeductionsMember" name="OtherSalesRelatedDeductionsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_PDGFRbetaoutsidetheUSMember" name="PDGFRbetaoutsidetheUSMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Paymenttoacquirepreferredshareofnonpublicentity" name="Paymenttoacquirepreferredshareofnonpublicentity" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element id="regn_PercentageOfTrialCostsBorneByCollaboratingParty" name="PercentageOfTrialCostsBorneByCollaboratingParty" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_PercentageOfTrialCostsBorneByEntity" name="PercentageOfTrialCostsBorneByEntity" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_PercentageofdevelopmentcostfortheterritoryoutsidetheUnitedStatestobepaidforunderthecollaboration" name="PercentageofdevelopmentcostfortheterritoryoutsidetheUnitedStatestobepaidforunderthecollaboration" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Percentageofdevelopmentmilestonepaymentstobereimbursed" name="Percentageofdevelopmentmilestonepaymentstobereimbursed" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Percentageofglobaldevelopmentcosttobepaidbythecollaborationpartnerunderthecollaboration" name="Percentageofglobaldevelopmentcosttobepaidbythecollaborationpartnerunderthecollaboration" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_PeriodForAchievingSalesTargetForMilestonePaymentRollingBasis" name="PeriodForAchievingSalesTargetForMilestonePaymentRollingBasis" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Prepaymentofcollaborationresearchcosts" name="Prepaymentofcollaborationresearchcosts" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_RebatesAndChargebacksMember" name="RebatesAndChargebacksMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ResearchAndDevelopmentArrangementContractToPerformForOthersByProductAxis" name="ResearchAndDevelopmentArrangementContractToPerformForOthersByProductAxis" nillable="true" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_ResearchAndDevelopmentArrangementContractToPerformForOthersByProductDomain" name="ResearchAndDevelopmentArrangementContractToPerformForOthersByProductDomain" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_RevenueAndConcentrationRiskDisclosureTextBlock" name="RevenueAndConcentrationRiskDisclosureTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_RevenueDisclosureTable" name="RevenueDisclosureTable" nillable="true" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_Salesachievement1billionMember" name="Salesachievement1billionMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_Salesachievement200millionMember" name="Salesachievement200millionMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_Salesachievement500millionMember" name="Salesachievement500millionMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_Salesachievement600millionMember" name="Salesachievement600millionMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_ScheduleOfSalesRelatedDeductionsActivityTableTextBlock" name="ScheduleOfSalesRelatedDeductionsActivityTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_Tradingdaystocalculatesettlement" name="Tradingdaystocalculatesettlement" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="regn_USGovernmentGuaranteedCorporateBondsMember" name="USGovernmentGuaranteedCorporateBondsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="regn_USGovernmentObligationsFairValueDisclosure" name="USGovernmentObligationsFairValueDisclosure" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
</xsd:schema>
