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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,
 Gnquq+jm04y7KeqVX8YDjldeB91F3lAXbQNGBoac6XP5vk3RXiRRC/Hyp+nhbFwZ
 pwdeagd414G6CRe8mHbV9w==

<SEC-DOCUMENT>0001181431-11-002572.txt : 20110107
<SEC-HEADER>0001181431-11-002572.hdr.sgml : 20110107
<ACCEPTANCE-DATETIME>20110107173112
ACCESSION NUMBER:		0001181431-11-002572
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20110106
FILED AS OF DATE:		20110107
DATE AS OF CHANGE:		20110107

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Tucker Winselow S. Jr.
		CENTRAL INDEX KEY:			0001492806

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-31141
		FILM NUMBER:		11518410

	MAIL ADDRESS:	
		STREET 1:		780 MEMORIAL DRIVE
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02139

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			INFINITY PHARMACEUTICALS, INC.
		CENTRAL INDEX KEY:			0001113148
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				330655706
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		780 MEMORIAL DRIVE
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02139
		BUSINESS PHONE:		6174531000

	MAIL ADDRESS:	
		STREET 1:		780 MEMORIAL DRIVE
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02139

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	INFINITY PHARMACEUTICALS, INC./NEW/
		DATE OF NAME CHANGE:	20060913

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	DISCOVERY PARTNERS INTERNATIONAL INC
		DATE OF NAME CHANGE:	20000428
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>rrd297131.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2011-01-06</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001113148</issuerCik>
        <issuerName>INFINITY PHARMACEUTICALS, INC.</issuerName>
        <issuerTradingSymbol>INFI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001492806</rptOwnerCik>
            <rptOwnerName>Tucker Winselow S. Jr.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O INFINITY PHARMACEUTICALS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>780 MEMORIAL DRIVE</rptOwnerStreet2>
            <rptOwnerCity>CAMBRIDGE</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02139</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Vice President, Marketing</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>5.94</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2011-01-06</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>6552</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2021-01-06</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>6552</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>6552</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The option vests as to 1/48th of the shares on January 31, 2011 and vests as to 1/48th of the shares at the end of each calendar month thereafter.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Winselow S. Tucker</signatureName>
        <signatureDate>2011-01-07</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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