<SEC-DOCUMENT>0001415889-12-001793.txt : 20121129
<SEC-HEADER>0001415889-12-001793.hdr.sgml : 20121129
<ACCEPTANCE-DATETIME>20121129203659
ACCESSION NUMBER:		0001415889-12-001793
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20121127
FILED AS OF DATE:		20121129
DATE AS OF CHANGE:		20121129

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Baity Glenn
		CENTRAL INDEX KEY:			0001487100

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-50768
		FILM NUMBER:		121233002

	MAIL ADDRESS:	
		STREET 1:		3911 SORRENTO VALLEY BLVD.
		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>form4-11292012_051150.xml
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2012-11-27</periodOfReport>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001487100</rptOwnerCik>
            <rptOwnerName>Baity Glenn</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>VP AND GC</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2012-11-27</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>16206</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>6.2788</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>47559</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2012-11-28</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>4396</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>5.2526</value>
                    <footnoteId id="F4"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>43163</value>
                </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 March 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 $6.03 to $6.50 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 ranges set forth in footnotes 2 and 4 to this Form 4.</footnote>
        <footnote id="F3">Includes an aggregate of 39,559 shares acquired by Mr. Baity under the ACADIA Pharmaceuticals Employee Stock Purchase Plan since inception.</footnote>
        <footnote id="F4">The price reported in Column 4 is a weighted-average price. These shares were sold in multiple transactions at prices ranging from $5.24 to $5.26 per share, inclusive.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Glenn F. Baity</signatureName>
        <signatureDate>2012-11-29</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
