-----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,
 Gv4RI0MH0fNh+5KkgwPFZcK7KXygMPt58FhYo+X80U7VqEc3n7IP/oIg7Ynwi5YY
 AVUIhT2w1nmY5SFM8vFfqQ==

<SEC-DOCUMENT>0000898432-04-000552.txt : 20040622
<SEC-HEADER>0000898432-04-000552.hdr.sgml : 20040622
<ACCEPTANCE-DATETIME>20040622135522
ACCESSION NUMBER:		0000898432-04-000552
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20040618
FILED AS OF DATE:		20040622

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			BVF INC/IL
		CENTRAL INDEX KEY:			0001056807

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-31161
		FILM NUMBER:		04874348

	BUSINESS ADDRESS:	
		STREET 1:		227 WEST MONROE STE
		STREET 2:		STE 4800
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60606
		BUSINESS PHONE:		3122637777

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ARENA PHARMACEUTICALS INC
		CENTRAL INDEX KEY:			0001080709
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				232908305
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		6166 NANCY RIDGE DR
		CITY:			SAN DIEGO
		STATE:			CA
		ZIP:			92121
		BUSINESS PHONE:		8584537200

	MAIL ADDRESS:	
		STREET 1:		6166 NANCY RIDGE DR
		CITY:			SAN DIEGO
		STATE:			CA
		ZIP:			92121

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			BIOTECHNOLOGY VALUE FUND L P
		CENTRAL INDEX KEY:			0000918923
		STANDARD INDUSTRIAL CLASSIFICATION:	INVESTMENT ADVICE [6282]
		STATE OF INCORPORATION:			DE

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-31161
		FILM NUMBER:		04874351

	BUSINESS ADDRESS:	
		STREET 1:		227 W MONROE STREET, SUITE 4800
		STREET 2:		227 W MONROE STREET, SUITE 4800
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60606
		BUSINESS PHONE:		415-288-23

	MAIL ADDRESS:	
		STREET 1:		227 W MONROE STREET, SUITE 4800
		STREET 2:		227 W MONROE STREET, SUITE 4800
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60606

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			BVF PARTNERS L P/IL
		CENTRAL INDEX KEY:			0001055947

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-31161
		FILM NUMBER:		04874352

	BUSINESS ADDRESS:	
		STREET 1:		ONE SANSOME ST
		STREET 2:		39TH FL
		CITY:			SAN FRANCISCO
		STATE:			CA
		ZIP:			94104
		BUSINESS PHONE:		3122637777

	MAIL ADDRESS:	
		STREET 1:		227 W MONROE
		STREET 2:		SUITE 4800
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60606

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			BIOTECHNOLOGY VALUE FUND II LP
		CENTRAL INDEX KEY:			0001102444
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-31161
		FILM NUMBER:		04874350

	BUSINESS ADDRESS:	
		STREET 1:		ONE SANSOME ST
		STREET 2:		39TH FL.
		CITY:			SAN FRANCISCO
		STATE:			CA
		ZIP:			94104
		BUSINESS PHONE:		3122637777

	MAIL ADDRESS:	
		STREET 1:		C/O GROSVENOR CAPITAL MANAGEMENT
		STREET 2:		227 W. MONROE ST #4800
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60606

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			BVF INVESTMENTS LLC
		CENTRAL INDEX KEY:			0001132245
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-31161
		FILM NUMBER:		04874349

	BUSINESS ADDRESS:	
		STREET 1:		ONE SANSOME ST. 39TH FL
		CITY:			SAN FRANCISCO
		STATE:			CA
		ZIP:			94104
		BUSINESS PHONE:		3127392123

	MAIL ADDRESS:	
		STREET 1:		C/O GROSVENOR CAPITAL MANAGEMENT LP
		STREET 2:		227 W. MONROE ST. #4800
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60606
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>arena-pharma_4ex.xml
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2004-06-18</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001080709</issuerCik>
        <issuerName>ARENA PHARMACEUTICALS INC</issuerName>
        <issuerTradingSymbol>ARNA</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001055947</rptOwnerCik>
            <rptOwnerName>BVF PARTNERS L P/IL</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>227 WEST MONROE STREET</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 4800</rptOwnerStreet2>
            <rptOwnerCity>CHICAGO</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60606</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>Indirect Beneficial Owner</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000918923</rptOwnerCik>
            <rptOwnerName>BIOTECHNOLOGY VALUE FUND L P</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>227 W MONROE STREET, SUITE 4800</rptOwnerStreet1>
            <rptOwnerStreet2>227 W MONROE STREET, SUITE 4800</rptOwnerStreet2>
            <rptOwnerCity>CHICAGO</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60606</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>Direct Beneficial Owner</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001102444</rptOwnerCik>
            <rptOwnerName>BIOTECHNOLOGY VALUE FUND II LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>ONE SANSOME ST</rptOwnerStreet1>
            <rptOwnerStreet2>39TH FL.</rptOwnerStreet2>
            <rptOwnerCity>SAN FRANCISCO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94104</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>Direct Beneficial Owner</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001132245</rptOwnerCik>
            <rptOwnerName>BVF INVESTMENTS LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>ONE SANSOME ST. 39TH FL</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SAN FRANCISCO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94104</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>Direct Beneficial Owner</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001056807</rptOwnerCik>
            <rptOwnerName>BVF INC/IL</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>227 WEST MONROE STE</rptOwnerStreet1>
            <rptOwnerStreet2>STE 4800</rptOwnerStreet2>
            <rptOwnerCity>CHICAGO</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60606</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>Indirect Beneficial Owner</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2004-06-18</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>2000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>5.519</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>886477</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnotes</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2004-06-18</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>5.519</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>570884</value>
                    <footnoteId id="F4"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnotes</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2004-06-18</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>3000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>5.519</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1502351</value>
                    <footnoteId id="F5"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnotes</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The shares reported in this response are beneficially owned by Biotechnology Value Fund, L.P., a Delaware limited partnership
(&quot;BVF, L.P.&quot;) (886,477 shares); Biotechnology Value Fund II, L.P., a Delaware limited partnership (&quot;BVF2, L.P.&quot;) (570,884
shares); BVF Investments, L.L.C., a Delaware limited liability company (&quot;Investments&quot;) (1,502,351 shares); and by BVF
Partners L.P., a Delaware limited partnership (&quot;Partners&quot;), and by its general partner BVF Inc., a Delaware corporation
(&quot;BVF Inc.&quot;), which is also an investment advisor to Partners. Partners is the general partner of BVF, L.P. and BVF2, L.P.
and is the manager of Investments. Pursuant to the operating agreement of Investments, Partners is authorized, among other
things, to invest the funds of Ziff Asset Management, L.P., the majority member of Investments, in the shares of common
stock described herein as being beneficially owned by Investments.</footnote>
        <footnote id="F2">Mark N. Lampert is the sole shareholder and sole director of BVF Inc., and is an officer of BVF Inc. This joint filing on
Form 4 shall not be deemed an admission that Mark N. Lampert is, for purposes of Section 16 of the Securities Exchange
Act of 1934, as amended, or otherwise, the beneficial owner of any equity securities covered by this joint filing.
Mr. Lampert disclaims beneficial ownership of shares reported in this response, except to the extent that he has a
pecuniary interest therein.</footnote>
        <footnote id="F3">Shares beneficially owned by BVF, L.P.</footnote>
        <footnote id="F4">Shares beneficially owned by BVF2, L.P.</footnote>
        <footnote id="F5">Shares beneficially owned by Investments.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>By: /s/ BVF Partners L.P., By: BVF Inc., its GP, By: /s/ Mark N. Lampert</signatureName>
        <signatureDate>2004-06-22</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>By: /s/ BIOTECHNOLOGY VALUE FUND, L.P. By: BVF Partners L.P., its GP, By: BVF Inc., By: /s/ Mark N. Lampert</signatureName>
        <signatureDate>2004-06-22</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>By: /s/ BIOTECHNOLOGY VALUE FUND II, L.P., By: BVF Partners L.P., its GP, By: BVF Inc., By: /s/ Mark N. Lampert</signatureName>
        <signatureDate>2004-06-22</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>By: /s/ BVF INVESTMENTS, L.L.C., By: BVF Partners L.P., its Manager, By: BVF Inc., By: /s/ Mark N. Lampert</signatureName>
        <signatureDate>2004-06-22</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>By: /s/ BVF INC., By: /s/ Mark N. Lampert</signatureName>
        <signatureDate>2004-06-22</signatureDate>
    </ownerSignature>
</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----