<SEC-DOCUMENT>0001415889-13-000635.txt : 20130403
<SEC-HEADER>0001415889-13-000635.hdr.sgml : 20130403
<ACCEPTANCE-DATETIME>20130403180841
ACCESSION NUMBER:		0001415889-13-000635
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20130401
FILED AS OF DATE:		20130403
DATE AS OF CHANGE:		20130403

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Mills Roger
		CENTRAL INDEX KEY:			0001368190

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-50768
		FILM NUMBER:		13741001

	MAIL ADDRESS:	
		STREET 1:		3911 SORRENTO VALLEY BOULEVARD
		CITY:			SAN DIEGO
		STATE:			CA
		ZIP:			92121

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ACADIA PHARMACEUTICALS INC
		CENTRAL INDEX KEY:			0001070494
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				061376651
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		3911 SORRENTO VALLEY BLVD
		CITY:			SAN DIEGO
		STATE:			CA
		ZIP:			92121
		BUSINESS PHONE:		858-558-2871

	MAIL ADDRESS:	
		STREET 1:		3911 SORRENTO VALLEY BLVD
		CITY:			SAN DIEGO
		STATE:			CA
		ZIP:			92121
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>form4-04032013_100428.xml
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2013-04-01</periodOfReport>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001368190</rptOwnerCik>
            <rptOwnerName>Mills Roger</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>3911 SORRENTO VALLEY BLVD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SAN DIEGO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>92121</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>false</isDirector>
            <isOfficer>true</isOfficer>
            <isTenPercentOwner>false</isTenPercentOwner>
            <isOther>false</isOther>
            <officerTitle>EVP, DEVELOPMENT AND CMO</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2013-04-01</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>58584</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>7.6875</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>14017</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person in 2012.</footnote>
        <footnote id="F2">The price reported in Column 4 is a weighted-average price. These shares were sold in multiple transactions at prices ranging from $7.59 to $7.90 per share, inclusive. The reporting person undertakes to provide ACADIA Pharmaceuticals Inc., any security holder of ACADIA Pharmaceuticals Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the foregoing range.</footnote>
        <footnote id="F3">All shares reflected in the this filing, including the shares sold and the remaining 14,017 shares, were acquired by Dr. Mills under the ACADIA Pharmaceuticals Employee Stock Purchase Plan.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Roger G. Mills</signatureName>
        <signatureDate>2013-04-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
