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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 A3FnxY4VANBDiLW100XUoZp6RaMkORD2Q3rbQe5Z0tdOpKsz6+n18vLjzgowWgVs
 pHbw0fr3rPDlg9p6Y9/HSw==

<SEC-DOCUMENT>0001446732-09-000076.txt : 20090430
<SEC-HEADER>0001446732-09-000076.hdr.sgml : 20090430
<ACCEPTANCE-DATETIME>20090430165229
ACCESSION NUMBER:		0001446732-09-000076
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20090428
FILED AS OF DATE:		20090430
DATE AS OF CHANGE:		20090430

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			COLLINS TED
		CENTRAL INDEX KEY:			0001234495

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-16295
		FILM NUMBER:		09784614

	MAIL ADDRESS:	
		STREET 1:		508 W WALL AVE SUITE 1200
		CITY:			MIDLAND
		STATE:			TX
		ZIP:			79701

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ENCORE ACQUISITION CO
		CENTRAL INDEX KEY:			0001125057
		STANDARD INDUSTRIAL CLASSIFICATION:	CRUDE PETROLEUM & NATURAL GAS [1311]
		IRS NUMBER:				752759650
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		777 MAIN STREET, SUITE 1400
		CITY:			FORT WORTH
		STATE:			TX
		ZIP:			76102
		BUSINESS PHONE:		8178779955
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2009-04-28</periodOfReport>

    <issuer>
        <issuerCik>0001125057</issuerCik>
        <issuerName>ENCORE ACQUISITION CO</issuerName>
        <issuerTradingSymbol>EAC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001234495</rptOwnerCik>
            <rptOwnerName>COLLINS TED</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>777 MAIN STREET</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 1400</rptOwnerStreet2>
            <rptOwnerCity>FORT WORTH</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>76102</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-04-28</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>5000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>129750</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes></footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Robert C. Reeves (attorney-in-fact)</signatureName>
        <signatureDate>2009-04-30</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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