<SUBMISSION>
<ACCESSION-NUMBER>0001012975-08-000083
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>2
<PERIOD>20080613
<FILING-DATE>20080617
<DATE-OF-FILING-DATE-CHANGE>20080617
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>ACADIA PHARMACEUTICALS INC
<CIK>0001070494
<ASSIGNED-SIC>2834
<IRS-NUMBER>061376651
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>3911 SORRENTO VALLEY BLVD
<CITY>SAN DIEGO
<STATE>CA
<ZIP>92121
<PHONE>858-558-2871
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>3911 SORRENTO VALLEY BLVD
<CITY>SAN DIEGO
<STATE>CA
<ZIP>92121
</MAIL-ADDRESS>
</ISSUER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>WALTON ALAN G
<CIK>0001214273
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>000-50768
<FILM-NUMBER>08904382
</FILING-VALUES>
<MAIL-ADDRESS>
<STREET1>ALEXANDRIA REAL ESTATE EQUITIES INC
<STREET2>135 N LOS ROBLES AVE SUITE 250
<CITY>PASADENA
<STATE>CA
<ZIP>91101
</MAIL-ADDRESS>
</REPORTING-OWNER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-06-13</periodOfReport>

    <issuer>
        <issuerCik>0001070494</issuerCik>
        <issuerName>ACADIA PHARMACEUTICALS INC</issuerName>
        <issuerTradingSymbol>ACAD</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001214273</rptOwnerCik>
            <rptOwnerName>WALTON ALAN G</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>315 POST ROAD WEST</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>WESTPORT</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06880</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>8.49</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2008-06-13</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>10000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2018-06-12</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>10000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>10000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>8.49</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2008-06-13</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>8833</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2018-06-12</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>8833</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>8833</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">One-Fourth of the shares subject to the Stock Option shall vest and become exercisable at the end of each three-month period followng June 13, 2008.</footnote>
        <footnote id="F2">The Reporting Person has elected to convert annual retainer fees of $25,000 into a stock option under the terms of the Issuer's Outside Director Compensation Program.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>___/s/ Raymond Charest_____________  Raymond Charest, as Attorney-in-Fact for Alan Walton</signatureName>
        <signatureDate>2008-06-17</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-24
<SEQUENCE>2
<FILENAME>attach_4.htm
<TEXT>
<HTML><BODY><PRE>

POWER OF ATTORNEY



 KNOW ALL MEN BY THESE PRESENTS, that each person whose signature appears below hereby constitutes and appoints Raymond Charest, Alexia Pearsall and Jonathan J. Fleming, and each of them, with full power to act without the other, his true and lawful attorney-in-fact and agent, with full power of substitution, for him and in his name, place and stead, in any and all capacities (until revoked in writing) to sign any and all instruments, certificates and documents required to be executed on behalf of himself as an individual or in his capacity as a general partner or authorized signatory, as the case may be, on behalf of any of Oxford Bioscience Partners IV L.P., mRNA II L.P., or OBP Management IV L.P., pursuant to section 13 or 16 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), and any and all regulations promulgated thereunder and to file the same, with all exhibits thereto, and any other documents in connection therewith, with the Securities and Exchange Commission, and with any other entity when and if such is mandated by the Exchange Act or by the By-laws of the National Association of Securities Dealers, Inc., granting unto said attorney-in-fact and agent full power and authority to do and perform each and every act and thing requisite and necessary fully to all intents and purposes as he might or could do in person thereby ratifying and confirming all that said attorney-in-fact and agent, or his substitute or substitutes, may lawfully do or cause to be done by virtue hereof, or may have done in connection with the matters described above.

IN WITNESS WHEREOF, this Power of Attorney has been signed as of the 8th day of April, 2004.





                               OXFORD BIOSCIENCE PARTNERS IV L.P.

                               by its General Partner, OBP MANAGEMENT IV L.P.





By: /s/ Jonathan Fleming

Name:  Jonathan J. Fleming

Title:  General Partner





    MRNA FUND II L.P.

    By its General Partner, OBP MANAGEMENT IV L.P.





By: /s/ Jonathan Fleming

    Name:  Jonathan J. Fleming

    Title:  General Partner





    OBP MANAGEMENT IV L.P.





By:/s/ Jonathan Fleming     ______

    Name:  Jonathan J. Fleming

    Title:  General Partner







/s/ Jeffrey T. Barnes     ______

    Jeffrey T. Barnes







/s/ Mark P. Carthy

    Mark P. Carthy







/s/ Jonathan J. Fleming

    Jonathan J. Fleming







/s/ Michael E. Lytton

    Michael E. Lytton







/s/ Alan G. Walton

    Alan G. Walton





















































</PRE></BODY></HTML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
