<?xml version="1.0" encoding="US-ASCII"?>
<!-- Generated by Fujitsu Interstage XWand B0160 -->
<link:linkbase xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xlink="http://www.w3.org/1999/xlink">
  <link:roleRef roleURI="http://www.momentapharma.com/role/BalanceSheet" xlink:type="simple" xlink:href="mnta-20110930.xsd#BalanceSheet"/>
  <link:roleRef roleURI="http://www.momentapharma.com/role/StatementOfIncome" xlink:type="simple" xlink:href="mnta-20110930.xsd#StatementOfIncome"/>
  <link:roleRef roleURI="http://www.momentapharma.com/role/CashFlows" xlink:type="simple" xlink:href="mnta-20110930.xsd#CashFlows"/>
  <link:calculationLink xlink:type="extended" xlink:role="http://www.momentapharma.com/role/BalanceSheet">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_Assets" xlink:label="Assets" xlink:title="Assets"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AssetsCurrent" xlink:label="AssetsCurrent" xlink:title="AssetsCurrent"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="Assets" xlink:to="AssetsCurrent" xlink:title="calculation: Assets to AssetsCurrent" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="CashAndCashEquivalentsAtCarryingValue" xlink:title="CashAndCashEquivalentsAtCarryingValue"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AssetsCurrent" xlink:to="CashAndCashEquivalentsAtCarryingValue" xlink:title="calculation: AssetsCurrent to CashAndCashEquivalentsAtCarryingValue" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AvailableForSaleSecuritiesCurrent" xlink:label="AvailableForSaleSecuritiesCurrent" xlink:title="AvailableForSaleSecuritiesCurrent"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AssetsCurrent" xlink:to="AvailableForSaleSecuritiesCurrent" xlink:title="calculation: AssetsCurrent to AvailableForSaleSecuritiesCurrent" order="2.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AccountsReceivableNetCurrent" xlink:label="AccountsReceivableNetCurrent" xlink:title="AccountsReceivableNetCurrent"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AssetsCurrent" xlink:to="AccountsReceivableNetCurrent" xlink:title="calculation: AssetsCurrent to AccountsReceivableNetCurrent" order="3.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_UnbilledContractsReceivable" xlink:label="UnbilledContractsReceivable" xlink:title="UnbilledContractsReceivable"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AssetsCurrent" xlink:to="UnbilledContractsReceivable" xlink:title="calculation: AssetsCurrent to UnbilledContractsReceivable" order="4.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:label="PrepaidExpenseAndOtherAssetsCurrent" xlink:title="PrepaidExpenseAndOtherAssetsCurrent"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AssetsCurrent" xlink:to="PrepaidExpenseAndOtherAssetsCurrent" xlink:title="calculation: AssetsCurrent to PrepaidExpenseAndOtherAssetsCurrent" order="5.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="PropertyPlantAndEquipmentNet" xlink:title="PropertyPlantAndEquipmentNet"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="Assets" xlink:to="PropertyPlantAndEquipmentNet" xlink:title="calculation: Assets to PropertyPlantAndEquipmentNet" order="2.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="FiniteLivedIntangibleAssetsNet" xlink:title="FiniteLivedIntangibleAssetsNet"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="Assets" xlink:to="FiniteLivedIntangibleAssetsNet" xlink:title="calculation: Assets to FiniteLivedIntangibleAssetsNet" order="3.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsNoncurrent" xlink:label="RestrictedCashAndCashEquivalentsNoncurrent" xlink:title="RestrictedCashAndCashEquivalentsNoncurrent"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="Assets" xlink:to="RestrictedCashAndCashEquivalentsNoncurrent" xlink:title="calculation: Assets to RestrictedCashAndCashEquivalentsNoncurrent" order="4.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="LiabilitiesAndStockholdersEquity" xlink:title="LiabilitiesAndStockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_Liabilities" xlink:label="Liabilities" xlink:title="Liabilities"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="LiabilitiesAndStockholdersEquity" xlink:to="Liabilities" xlink:title="calculation: LiabilitiesAndStockholdersEquity to Liabilities" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_LiabilitiesCurrent" xlink:label="LiabilitiesCurrent" xlink:title="LiabilitiesCurrent"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="Liabilities" xlink:to="LiabilitiesCurrent" xlink:title="calculation: Liabilities to LiabilitiesCurrent" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AccountsPayableCurrent" xlink:label="AccountsPayableCurrent" xlink:title="AccountsPayableCurrent"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="LiabilitiesCurrent" xlink:to="AccountsPayableCurrent" xlink:title="calculation: LiabilitiesCurrent to AccountsPayableCurrent" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AccruedLiabilitiesCurrent" xlink:label="AccruedLiabilitiesCurrent" xlink:title="AccruedLiabilitiesCurrent"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="LiabilitiesCurrent" xlink:to="AccruedLiabilitiesCurrent" xlink:title="calculation: LiabilitiesCurrent to AccruedLiabilitiesCurrent" order="2.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredRevenueCurrent" xlink:label="DeferredRevenueCurrent" xlink:title="DeferredRevenueCurrent"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="LiabilitiesCurrent" xlink:to="DeferredRevenueCurrent" xlink:title="calculation: LiabilitiesCurrent to DeferredRevenueCurrent" order="3.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_CapitalLeaseObligationsCurrent" xlink:label="CapitalLeaseObligationsCurrent" xlink:title="CapitalLeaseObligationsCurrent"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="LiabilitiesCurrent" xlink:to="CapitalLeaseObligationsCurrent" xlink:title="calculation: LiabilitiesCurrent to CapitalLeaseObligationsCurrent" order="4.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="mnta-20110930.xsd#mnta_LeaseFinancingLiabilityCurrent" xlink:label="LeaseFinancingLiabilityCurrent" xlink:title="LeaseFinancingLiabilityCurrent"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="LiabilitiesCurrent" xlink:to="LeaseFinancingLiabilityCurrent" xlink:title="calculation: LiabilitiesCurrent to LeaseFinancingLiabilityCurrent" order="5.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredRentCreditCurrent" xlink:label="DeferredRentCreditCurrent" xlink:title="DeferredRentCreditCurrent"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="LiabilitiesCurrent" xlink:to="DeferredRentCreditCurrent" xlink:title="calculation: LiabilitiesCurrent to DeferredRentCreditCurrent" order="6.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredRevenueNoncurrent" xlink:label="DeferredRevenueNoncurrent" xlink:title="DeferredRevenueNoncurrent"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="Liabilities" xlink:to="DeferredRevenueNoncurrent" xlink:title="calculation: Liabilities to DeferredRevenueNoncurrent" order="2.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherLiabilitiesNoncurrent" xlink:label="OtherLiabilitiesNoncurrent" xlink:title="OtherLiabilitiesNoncurrent"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="Liabilities" xlink:to="OtherLiabilitiesNoncurrent" xlink:title="calculation: Liabilities to OtherLiabilitiesNoncurrent" order="3.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="StockholdersEquity" xlink:title="StockholdersEquity"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="LiabilitiesAndStockholdersEquity" xlink:to="StockholdersEquity" xlink:title="calculation: LiabilitiesAndStockholdersEquity to StockholdersEquity" order="2.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_PreferredStockValue" xlink:label="PreferredStockValue" xlink:title="PreferredStockValue"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="StockholdersEquity" xlink:to="PreferredStockValue" xlink:title="calculation: StockholdersEquity to PreferredStockValue" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_CommonStockValue" xlink:label="CommonStockValue" xlink:title="CommonStockValue"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="StockholdersEquity" xlink:to="CommonStockValue" xlink:title="calculation: StockholdersEquity to CommonStockValue" order="2.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AdditionalPaidInCapital" xlink:label="AdditionalPaidInCapital" xlink:title="AdditionalPaidInCapital"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="StockholdersEquity" xlink:to="AdditionalPaidInCapital" xlink:title="calculation: StockholdersEquity to AdditionalPaidInCapital" order="3.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:label="AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:title="AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="StockholdersEquity" xlink:to="AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:title="calculation: StockholdersEquity to AccumulatedOtherComprehensiveIncomeLossNetOfTax" order="4.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="RetainedEarningsAccumulatedDeficit" xlink:title="RetainedEarningsAccumulatedDeficit"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="StockholdersEquity" xlink:to="RetainedEarningsAccumulatedDeficit" xlink:title="calculation: StockholdersEquity to RetainedEarningsAccumulatedDeficit" order="5.0" weight="1.0"/>
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://www.momentapharma.com/role/StatementOfIncome">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" xlink:label="NetIncomeLossAvailableToCommonStockholdersBasic" xlink:title="NetIncomeLossAvailableToCommonStockholdersBasic"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="OperatingIncomeLoss" xlink:title="OperatingIncomeLoss"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetIncomeLossAvailableToCommonStockholdersBasic" xlink:to="OperatingIncomeLoss" xlink:title="calculation: NetIncomeLossAvailableToCommonStockholdersBasic to OperatingIncomeLoss" use="optional" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_Revenues" xlink:label="Revenues" xlink:title="Revenues"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="OperatingIncomeLoss" xlink:to="Revenues" xlink:title="calculation: OperatingIncomeLoss to Revenues" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_SalesRevenueGoodsNet" xlink:label="SalesRevenueGoodsNet" xlink:title="SalesRevenueGoodsNet"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="Revenues" xlink:to="SalesRevenueGoodsNet" xlink:title="calculation: Revenues to SalesRevenueGoodsNet" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="mnta-20110930.xsd#mnta_ResearchAndDevelopmentRevenue" xlink:label="ResearchAndDevelopmentRevenue" xlink:title="ResearchAndDevelopmentRevenue"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="Revenues" xlink:to="ResearchAndDevelopmentRevenue" xlink:title="calculation: Revenues to ResearchAndDevelopmentRevenue" order="2.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OperatingExpenses" xlink:label="OperatingExpenses" xlink:title="OperatingExpenses"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="OperatingIncomeLoss" xlink:to="OperatingExpenses" xlink:title="calculation: OperatingIncomeLoss to OperatingExpenses" order="2.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ResearchAndDevelopmentExpense" xlink:label="ResearchAndDevelopmentExpense" xlink:title="ResearchAndDevelopmentExpense"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="OperatingExpenses" xlink:to="ResearchAndDevelopmentExpense" xlink:title="calculation: OperatingExpenses to ResearchAndDevelopmentExpense" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_GeneralAndAdministrativeExpense" xlink:label="GeneralAndAdministrativeExpense" xlink:title="GeneralAndAdministrativeExpense"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="OperatingExpenses" xlink:to="GeneralAndAdministrativeExpense" xlink:title="calculation: OperatingExpenses to GeneralAndAdministrativeExpense" order="2.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_NonoperatingIncomeExpense" xlink:label="NonoperatingIncomeExpense" xlink:title="NonoperatingIncomeExpense"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetIncomeLossAvailableToCommonStockholdersBasic" xlink:to="NonoperatingIncomeExpense" xlink:title="calculation: NetIncomeLossAvailableToCommonStockholdersBasic to NonoperatingIncomeExpense" use="optional" order="2.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_InvestmentIncomeInterest" xlink:label="InvestmentIncomeInterest" xlink:title="InvestmentIncomeInterest"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NonoperatingIncomeExpense" xlink:to="InvestmentIncomeInterest" xlink:title="calculation: NonoperatingIncomeExpense to InvestmentIncomeInterest" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_InterestExpense" xlink:label="InterestExpense" xlink:title="InterestExpense"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NonoperatingIncomeExpense" xlink:to="InterestExpense" xlink:title="calculation: NonoperatingIncomeExpense to InterestExpense" order="2.0" weight="-1.0"/>
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://www.momentapharma.com/role/CashFlows">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_NetCashProvidedByUsedInContinuingOperations" xlink:label="NetCashProvidedByUsedInContinuingOperations" xlink:title="NetCashProvidedByUsedInContinuingOperations"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:label="NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:title="NetCashProvidedByUsedInOperatingActivitiesContinuingOperations"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInContinuingOperations" xlink:to="NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:title="calculation: NetCashProvidedByUsedInContinuingOperations to NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" use="optional" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" xlink:label="NetIncomeLossAvailableToCommonStockholdersBasic" xlink:title="NetIncomeLossAvailableToCommonStockholdersBasic"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="NetIncomeLossAvailableToCommonStockholdersBasic" xlink:title="calculation: NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to NetIncomeLossAvailableToCommonStockholdersBasic" use="optional" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DepreciationDepletionAndAmortization" xlink:label="DepreciationDepletionAndAmortization" xlink:title="DepreciationDepletionAndAmortization"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="DepreciationDepletionAndAmortization" xlink:title="calculation: NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to DepreciationDepletionAndAmortization" use="optional" order="2.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ShareBasedCompensation" xlink:label="ShareBasedCompensation" xlink:title="ShareBasedCompensation"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="ShareBasedCompensation" xlink:title="calculation: NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to ShareBasedCompensation" use="optional" order="3.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments" xlink:label="AccretionAmortizationOfDiscountsAndPremiumsInvestments" xlink:title="AccretionAmortizationOfDiscountsAndPremiumsInvestments"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="AccretionAmortizationOfDiscountsAndPremiumsInvestments" xlink:title="calculation: NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to AccretionAmortizationOfDiscountsAndPremiumsInvestments" use="optional" order="4.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="AmortizationOfIntangibleAssets" xlink:title="AmortizationOfIntangibleAssets"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="AmortizationOfIntangibleAssets" xlink:title="calculation: NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to AmortizationOfIntangibleAssets" use="optional" order="5.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_GainLossOnDispositionOfProperty" xlink:label="GainLossOnDispositionOfProperty" xlink:title="GainLossOnDispositionOfProperty"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="GainLossOnDispositionOfProperty" xlink:title="calculation: NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to GainLossOnDispositionOfProperty" use="optional" order="6.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:label="IncreaseDecreaseInAccountsReceivable" xlink:title="IncreaseDecreaseInAccountsReceivable"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="IncreaseDecreaseInAccountsReceivable" xlink:title="calculation: NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to IncreaseDecreaseInAccountsReceivable" use="optional" order="7.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncreaseDecreaseInUnbilledReceivables" xlink:label="IncreaseDecreaseInUnbilledReceivables" xlink:title="IncreaseDecreaseInUnbilledReceivables"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="IncreaseDecreaseInUnbilledReceivables" xlink:title="calculation: NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to IncreaseDecreaseInUnbilledReceivables" use="optional" order="8.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:label="IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:title="IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:title="calculation: NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" use="optional" order="9.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsPayable" xlink:label="IncreaseDecreaseInAccountsPayable" xlink:title="IncreaseDecreaseInAccountsPayable"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="IncreaseDecreaseInAccountsPayable" xlink:title="calculation: NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to IncreaseDecreaseInAccountsPayable" use="optional" order="11.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncreaseDecreaseInAccruedLiabilities" xlink:label="IncreaseDecreaseInAccruedLiabilities" xlink:title="IncreaseDecreaseInAccruedLiabilities"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="IncreaseDecreaseInAccruedLiabilities" xlink:title="calculation: NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to IncreaseDecreaseInAccruedLiabilities" use="optional" order="12.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="mnta-20110930.xsd#mnta_IncreaseDecreaseInDeferredRent" xlink:label="IncreaseDecreaseInDeferredRent" xlink:title="IncreaseDecreaseInDeferredRent"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="IncreaseDecreaseInDeferredRent" xlink:title="calculation: NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to IncreaseDecreaseInDeferredRent" use="optional" order="13.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncreaseDecreaseInDeferredRevenue" xlink:label="IncreaseDecreaseInDeferredRevenue" xlink:title="IncreaseDecreaseInDeferredRevenue"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="IncreaseDecreaseInDeferredRevenue" xlink:title="calculation: NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to IncreaseDecreaseInDeferredRevenue" use="optional" order="14.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncreaseDecreaseInOtherNoncurrentLiabilities" xlink:label="IncreaseDecreaseInOtherNoncurrentLiabilities" xlink:title="IncreaseDecreaseInOtherNoncurrentLiabilities"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="IncreaseDecreaseInOtherNoncurrentLiabilities" xlink:title="calculation: NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to IncreaseDecreaseInOtherNoncurrentLiabilities" use="optional" order="15.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncreaseDecreaseInRestrictedCashForOperatingActivities" xlink:label="IncreaseDecreaseInRestrictedCashForOperatingActivities" xlink:title="IncreaseDecreaseInRestrictedCashForOperatingActivities"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="IncreaseDecreaseInRestrictedCashForOperatingActivities" xlink:title="calculation: NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to IncreaseDecreaseInRestrictedCashForOperatingActivities" use="optional" order="10.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:label="NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:title="NetCashProvidedByUsedInInvestingActivitiesContinuingOperations"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInContinuingOperations" xlink:to="NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:title="calculation: NetCashProvidedByUsedInContinuingOperations to NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" use="optional" order="2.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:label="PaymentsToAcquirePropertyPlantAndEquipment" xlink:title="PaymentsToAcquirePropertyPlantAndEquipment"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:to="PaymentsToAcquirePropertyPlantAndEquipment" xlink:title="calculation: NetCashProvidedByUsedInInvestingActivitiesContinuingOperations to PaymentsToAcquirePropertyPlantAndEquipment" use="optional" order="1.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_PaymentsToAcquireAvailableForSaleSecurities" xlink:label="PaymentsToAcquireAvailableForSaleSecurities" xlink:title="PaymentsToAcquireAvailableForSaleSecurities"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:to="PaymentsToAcquireAvailableForSaleSecurities" xlink:title="calculation: NetCashProvidedByUsedInInvestingActivitiesContinuingOperations to PaymentsToAcquireAvailableForSaleSecurities" use="optional" order="2.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities" xlink:label="ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities" xlink:title="ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:to="ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities" xlink:title="calculation: NetCashProvidedByUsedInInvestingActivitiesContinuingOperations to ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities" use="optional" order="3.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_PaymentsToAcquireIntangibleAssets" xlink:label="PaymentsToAcquireIntangibleAssets" xlink:title="PaymentsToAcquireIntangibleAssets"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:to="PaymentsToAcquireIntangibleAssets" xlink:title="calculation: NetCashProvidedByUsedInInvestingActivitiesContinuingOperations to PaymentsToAcquireIntangibleAssets" use="optional" order="4.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:label="NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:title="NetCashProvidedByUsedInFinancingActivitiesContinuingOperations"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInContinuingOperations" xlink:to="NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:title="calculation: NetCashProvidedByUsedInContinuingOperations to NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" use="optional" order="3.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions" xlink:label="ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions" xlink:title="ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions" xlink:title="calculation: NetCashProvidedByUsedInFinancingActivitiesContinuingOperations to ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions" use="optional" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="mnta-20110930.xsd#mnta_PaymentsOnFinancedLeaseholdImprovements" xlink:label="PaymentsOnFinancedLeaseholdImprovements" xlink:title="PaymentsOnFinancedLeaseholdImprovements"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="PaymentsOnFinancedLeaseholdImprovements" xlink:title="calculation: NetCashProvidedByUsedInFinancingActivitiesContinuingOperations to PaymentsOnFinancedLeaseholdImprovements" use="optional" order="2.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_RepaymentsOfDebtAndCapitalLeaseObligations" xlink:label="RepaymentsOfDebtAndCapitalLeaseObligations" xlink:title="RepaymentsOfDebtAndCapitalLeaseObligations"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="RepaymentsOfDebtAndCapitalLeaseObligations" xlink:title="calculation: NetCashProvidedByUsedInFinancingActivitiesContinuingOperations to RepaymentsOfDebtAndCapitalLeaseObligations" use="optional" order="3.0" weight="-1.0"/>
  </link:calculationLink>
</link:linkbase>
