<SUBMISSION>
<ACCESSION-NUMBER>0001191905-05-000004
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20050526
<FILING-DATE>20050531
<DATE-OF-FILING-DATE-CHANGE>20050531
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>KUMAR AMIT
<CIK>0001191905
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>000-26068
<FILM-NUMBER>05868552
</FILING-VALUES>
<BUSINESS-ADDRESS>
<PHONE>(949) 480-8300
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>C/O ACACIA RESEARCH CORPORATION
<STREET2>500 NEWPORT CENTER DRIVE, 7TH FLOOR
<CITY>NEWPORT BEACH
<STATE>CA
<ZIP>92660
</MAIL-ADDRESS>
</REPORTING-OWNER>
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>ACACIA RESEARCH CORP
<CIK>0000934549
<ASSIGNED-SIC>3670
<IRS-NUMBER>954405754
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>500 NEWPORT CENTER DRIVE
<STREET2>7TH FLOOR
<CITY>NEWPORT BEACH
<STATE>CA
<ZIP>92660
<PHONE>9494808300
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>500 NEWPORT CENTER DRIVE
<STREET2>#
<CITY>NEWPORT BEACH
<STATE>CA
<ZIP>92660
</MAIL-ADDRESS>
</ISSUER>
<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>2005-05-26</periodOfReport>

    <issuer>
        <issuerCik>0000934549</issuerCik>
        <issuerName>ACACIA RESEARCH CORP</issuerName>
        <issuerTradingSymbol>ACTG/CBMX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001191905</rptOwnerCik>
            <rptOwnerName>KUMAR AMIT</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>500 NEWPORT CENTER DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2>7TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEWPORT BEACH</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>92660</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Pres/CEO of CombiMatrix Corp.</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>2.98</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2005-05-26</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>90000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2015-05-26</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Acacia Research-CombiMatrix Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>90000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1211660</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The option shall become exercisable for 1/6 of the option shares upon Reporting Person's completion of 6 months of service measured from the grant date.  The balance of the option shares shall become exercisable in 30 successive equal montly installments upon Reporting Person's completion of each additional month of service.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Amit Kumar</signatureName>
        <signatureDate>2005-05-26</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
