-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
 FPRTh7y9s5Ck6sV6z6LhM4ch1z+6KsZVfD+zQaPQNJasM8B8AIIDhbG/wrXOu3F/
 6dvCr9ZbNJ6T28Dg6pE8sA==

<SEC-DOCUMENT>0001181431-08-050941.txt : 20080902
<SEC-HEADER>0001181431-08-050941.hdr.sgml : 20080901
<ACCEPTANCE-DATETIME>20080902142219
ACCESSION NUMBER:		0001181431-08-050941
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20080828
FILED AS OF DATE:		20080902
DATE AS OF CHANGE:		20080902

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ACHILLION PHARMACEUTICALS INC
		CENTRAL INDEX KEY:			0001070336
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				000000000

	BUSINESS ADDRESS:	
		STREET 1:		300 GEORGE STREET
		CITY:			NEW HAVEN
		STATE:			CT
		ZIP:			06511
		BUSINESS PHONE:		203-624-7000

	MAIL ADDRESS:	
		STREET 1:		300 GEORGE STREET
		CITY:			NEW HAVEN
		STATE:			CT
		ZIP:			06511

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Olek Elizabeth A
		CENTRAL INDEX KEY:			0001419066

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-33095
		FILM NUMBER:		081051284

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		203-624-7000

	MAIL ADDRESS:	
		STREET 1:		C/O ACHILLION PHARMACEUTICALS, INC.
		STREET 2:		300 GEORGE STREET
		CITY:			NEW HAVEN
		STATE:			CT
		ZIP:			06511
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>rrd217594.xml
<DESCRIPTION>OLEK STOCK PURCHASE 8/28/08
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-08-28</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001070336</issuerCik>
        <issuerName>ACHILLION PHARMACEUTICALS INC</issuerName>
        <issuerTradingSymbol>ACHN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001419066</rptOwnerCik>
            <rptOwnerName>Olek Elizabeth A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O ACHILLION PHARMACEUTICALS</rptOwnerStreet1>
            <rptOwnerStreet2>300 GEORGE STREET</rptOwnerStreet2>
            <rptOwnerCity>NEW HAVEN</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06511</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Vice President and CMO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-08-28</value>
            </transactionDate>
            <deemedExecutionDate>
                <value>2008-08-28</value>
            </deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>500</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.29</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>500</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-08-28</value>
            </transactionDate>
            <deemedExecutionDate>
                <value>2008-08-28</value>
            </deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1500</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.46</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <ownerSignature>
        <signatureName>/s/ Elizabeth A. Olek</signatureName>
        <signatureDate>2008-09-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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