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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 BA8YOvpA4bMja3Zy5Ji5HYPMtxcxcg/RuBXZkk3Ui0rNonoUfJZmEy6kgPmmXSoR
 GbRjMGEpSVOmXHAAOxLnwA==

<SEC-DOCUMENT>0001209191-05-046477.txt : 20050908
<SEC-HEADER>0001209191-05-046477.hdr.sgml : 20050908
<ACCEPTANCE-DATETIME>20050908175846
ACCESSION NUMBER:		0001209191-05-046477
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20050906
FILED AS OF DATE:		20050908
DATE AS OF CHANGE:		20050908

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			OSCIENT PHARMACEUTICALS CORP
		CENTRAL INDEX KEY:			0000356830
		STANDARD INDUSTRIAL CLASSIFICATION:	IN VITRO & IN VIVO DIAGNOSTIC SUBSTANCES [2835]
		IRS NUMBER:				042297484
		STATE OF INCORPORATION:			MA
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		1000 WINTER STREET
		STREET 2:		SUITE 2200
		CITY:			WALTHAM
		STATE:			MA
		ZIP:			02451
		BUSINESS PHONE:		7813982300

	MAIL ADDRESS:	
		STREET 1:		1000 WINTER STREET
		STREET 2:		SUITE 2200
		CITY:			WALTHAM
		STATE:			MA
		ZIP:			02451

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	GENOME THERAPEUTICS CORP
		DATE OF NAME CHANGE:	19941215

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	COLLABORATIVE RESEARCH INC
		DATE OF NAME CHANGE:	19920703

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			EVNIN LUKE
		CENTRAL INDEX KEY:			0001134657

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-10824
		FILM NUMBER:		051076181

	BUSINESS ADDRESS:	
		STREET 1:		ONE CAMBRIDGE CENTER
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02142
		BUSINESS PHONE:		6174259200

	MAIL ADDRESS:	
		STREET 1:		C/O MPM ASSET MANAGEMENT
		STREET 2:		111 HUNTINGTON AVE., 31ST FLOOR
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02199
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>bsf12386_5le.xml
<DESCRIPTION>MAIN DOCUMENT DESCRIPTION
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-09-06</periodOfReport>

    <issuer>
        <issuerCik>0000356830</issuerCik>
        <issuerName>OSCIENT PHARMACEUTICALS CORP</issuerName>
        <issuerTradingSymbol>OSCI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001134657</rptOwnerCik>
            <rptOwnerName>EVNIN LUKE</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O MPM ASSET MANAGEMENT</rptOwnerStreet1>
            <rptOwnerStreet2>111 HUNTINGTON AVE., 31ST FLOOR</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02199</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2005-09-06</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>200000</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.4678</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4587050</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2005-09-06</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>42000</value>
                    <footnoteId id="F3"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.583</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4545050</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F4"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The shares were sold as follows: 175,170 by BB BioVentures L.P. (&quot;BB BV&quot;), 22,530 by MPM BioVentures Parallel Fund, L.P. (&quot;BV PF&quot;) and 2,300 by MPM Asset Management Investors 1998 LLC (&quot;AM 1998&quot;).    MPM BioVentures I, L.P. (&quot;BV I&quot;) and MPM BioVentures I LLC (&quot;BV I LLC&quot;) are the direct and indirect general partners of BV PF.  BAB BioVentures L.P. (&quot;BAB BV&quot;) and BAB BioVentures, N.V. (&quot;BAB NV&quot;) are the direct and indirect general partners of BB BV.   The Reporting Person is a manager of BAB NV, AM 1998 and BV I LLC.</footnote>
        <footnote id="F2">The shares are held as follows: 4,017,547 by BB BV, 516,755 by BV PF and 52,748 by AM 1998.  The Reporting Person disclaims beneficial ownership of the securities except to the extent of its pecuniary interest therein.</footnote>
        <footnote id="F3">The shares were sold as follows: 36,786 by BB BV, 4,731 by BV PF and 483 by AM 1998.</footnote>
        <footnote id="F4">The shares are held as follows:  3,980,761 by BB BV, 512,024 by BV PF and 52,265 by AM 1998.  The Reporting Person disclaims beneficial ownership of the securities except to the extent of its pecuniary interest therein.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Luke Evnin</signatureName>
        <signatureDate>2005-09-08</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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