-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 ndUQvicwcR6ZC5l7lzTxYg==

<SEC-DOCUMENT>0001209191-05-043958.txt : 20050822
<SEC-HEADER>0001209191-05-043958.hdr.sgml : 20050822
<ACCEPTANCE-DATETIME>20050822192124
ACCESSION NUMBER:		0001209191-05-043958
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20050818
FILED AS OF DATE:		20050822
DATE AS OF CHANGE:		20050822

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:		051042254

	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>bsf12038_bsf1le.xml
<DESCRIPTION>MAIN DOCUMENT DESCRIPTION
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-08-18</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>2005-08-18</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>225000</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.5296</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>6947050</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>2005-08-19</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>60000</value>
                    <footnoteId id="F3"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.3528</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>6887050</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F4"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2005-08-19</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>100000</value>
                    <footnoteId id="F5"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.42</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>6787050</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F6"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2005-08-22</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>50000</value>
                    <footnoteId id="F7"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.2936</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>6737050</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F8"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2005-08-22</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>150000</value>
                    <footnoteId id="F9"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.28</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>6587050</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F10"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The shares were sold as follows: 197,067 by BB BioVentures L.P. (&quot;BB BV&quot;), 25,345 by MPM BioVentures Parallel Fund, L.P. (&quot;BV PF&quot;) and 2,588 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: 6,084,555 by BB BV, 782,607 by BV PF and 79,888 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: 52,551 by BB BV, 6,759 by BV PF and 690 by AM 1998.</footnote>
        <footnote id="F4">The shares are held as follows: 6,032,004 by BB BV, 775,848 by BV PF and 79,198 by AM 1998.  The Reporting Person disclaims beneficial ownership of the securities except to the extent of its pecuniary interest therein.</footnote>
        <footnote id="F5">The shares were sold as follows: 87,585 by BB BV, 11,265 by BV PF and 1,150 by AM 1998.</footnote>
        <footnote id="F6">The shares are held as follows: 5,944,419 by BB BV, 764,583 by BV PF and 78,048 by AM 1998.  The Reporting Person disclaims beneficial ownership of the securities except to the extent of its pecuniary interest therein.</footnote>
        <footnote id="F7">The shares were sold as follows:  43,793 by BB BV, 5,632 by BV PF and 575 by AM 1998.</footnote>
        <footnote id="F8">The shares are held as follows: 5,900,626 by BB BV, 758,951 by BV PF and 77,473 by AM 1998.  The Reporting Person disclaims beneficial ownership of the securities except to the extent of its pecuniary interest therein.</footnote>
        <footnote id="F9">The shares were sold as follows:  131,378 by BB BV, 16,897 by BV PF and 1,725 by AM 1998</footnote>
        <footnote id="F10">The shares are held as follows: 5,769,248 by BB BV, 742,054 by BV PF and 75,748 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>2005-08-22</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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