-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
 MFgwCgYEVQgBAQICAf8DSgAwRwJAW2sNKK9AVtBzYZmr6aGjlWyK3XmZv3dTINen
 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 HfrUeLstbNYwgqxO+sh5Y09I+8va/V7N6wwDo9rq9mk/Bg5D7p5myzTxViXhRJV/
 W+u/q46fb+3ZVpzfE5gShQ==

<SEC-DOCUMENT>0001209191-05-047280.txt : 20050914
<SEC-HEADER>0001209191-05-047280.hdr.sgml : 20050914
<ACCEPTANCE-DATETIME>20050914201501
ACCESSION NUMBER:		0001209191-05-047280
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20050914
FILED AS OF DATE:		20050914
DATE AS OF CHANGE:		20050914

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:		051085525

	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_13le.xml
<DESCRIPTION>MAIN DOCUMENT DESCRIPTION
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-09-14</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>2005-09-14</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>23975</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.4507</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4166075</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The shares were sold as follows: 20,998 by BB BioVentures L.P. (&quot;BB BV&quot;), 2,701 by MPM BioVentures Parallel Fund, L.P. (&quot;BV PF&quot;) and 276 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 member of one of the shareholders of BAB NV and a manager of AM 1998 and BV I LLC.</footnote>
        <footnote id="F2">The shares are held as follows: 3,648,835 by BB BV, 469,333 by BV PF and 47,907 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>2005-09-14</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----