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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
 EadkJHEVXMJyU+UIXmWYkQkVaDL1IGQFUjeCRml0YLYlv+6HXJ8cSG30kyP5T3gc
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<SEC-DOCUMENT>0001181431-05-069346.txt : 20051229
<SEC-HEADER>0001181431-05-069346.hdr.sgml : 20051229
<ACCEPTANCE-DATETIME>20051229185401
ACCESSION NUMBER:		0001181431-05-069346
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20051221
FILED AS OF DATE:		20051229
DATE AS OF CHANGE:		20051229

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			HENNESSEY ROBERT J
		CENTRAL INDEX KEY:			0001234374

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-10824
		FILM NUMBER:		051292521

	BUSINESS ADDRESS:	
		STREET 1:		100 BEAVER STREET
		CITY:			WALTHAM
		STATE:			MA
		ZIP:			02453
		BUSINESS PHONE:		7813982311

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			OSCIENT PHARMACEUTICALS CORP
		CENTRAL INDEX KEY:			0000356830
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		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
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>rrd101501.xml
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-12-21</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001234374</rptOwnerCik>
            <rptOwnerName>HENNESSEY ROBERT J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1000 WINTER ST. SUITE 2200</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>WALTHAM</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02451</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>1.57</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2005-12-21</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>5748</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2005-04-13</value>
            </exerciseDate>
            <expirationDate>
                <value>2014-04-12</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>5748</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>2.28</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2005-12-21</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>5748</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2005-12-21</value>
            </exerciseDate>
            <expirationDate>
                <value>2015-12-20</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>5748</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5748</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The discounted stock options were cancelled by mutual agreement of the reporting person and the Company and exchanged for the same amount of options exerciseable at the current fair market value on the transaction date in accordance with transition guidance issued by Internal Revenue Code, Section 409A.   Additionally, the reporting person received $6,119.54 as consideration for the cancellation and exchange.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Robert E. Farrell Jr Corp Controller/Treasurer  Power of Attorney</signatureName>
        <signatureDate>2005-12-29</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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