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<!--Created on: 4/22/2009 10:49:04 AM-->
<!--Modified on: 2/9/2010 2:48:13 PM-->
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  <element id="biib_RetirementOfCommonStockShares" name="RetirementOfCommonStockShares" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="biib_TreasuryStockReclassifications" name="TreasuryStockReclassifications" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" />
  <element id="biib_ShareholdersEquityTextBlock" name="ShareholdersEquityTextBlock" type="xbrli:normalizedStringItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
</schema>
</XBRL>
