<SUBMISSION>
<ACCESSION-NUMBER>0001025835-09-000073
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20090206
<FILING-DATE>20090206
<DATE-OF-FILING-DATE-CHANGE>20090206
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>ENTERPRISE FINANCIAL SERVICES CORP
<CIK>0001025835
<ASSIGNED-SIC>6022
<IRS-NUMBER>431706259
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>150 NORTH MERAMEC
<STREET2>150 NORTH MERAMEC
<CITY>CLAYTON
<STATE>MO
<ZIP>63105
<PHONE>3147255500
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>150 NORTH MERAMEC
<STREET2>150 NORTH MERAMEC
<CITY>CLAYTON
<STATE>MO
<ZIP>63105
</MAIL-ADDRESS>
<FORMER-COMPANY>
<FORMER-CONFORMED-NAME>ENTERBANK HOLDINGS INC
<DATE-CHANGED>19961024
</FORMER-COMPANY>
</ISSUER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>EICHNER KEVIN C
<CIK>0001176259
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-15373
<FILM-NUMBER>09577654
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>GREENSFELDER HEMKER & GALE PC
<STREET2>10 S BORADWAY 2000 EQUITABLE BLDG
<CITY>ST LOUIS
<STATE>MO
<ZIP>63102
<PHONE>3142413483
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>150 N MERAMEC
<STREET2>PO BOX 66940
<CITY>CLAYTON
<STATE>MO
<ZIP>63105
</MAIL-ADDRESS>
</REPORTING-OWNER>
<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>2009-02-06</periodOfReport>

    <issuer>
        <issuerCik>0001025835</issuerCik>
        <issuerName>ENTERPRISE FINANCIAL SERVICES CORP</issuerName>
        <issuerTradingSymbol>EFSC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001176259</rptOwnerCik>
            <rptOwnerName>EICHNER KEVIN C</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>150 N. MERAMEC</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>ST. LOUIS</rptOwnerCity>
            <rptOwnerState>MO</rptOwnerState>
            <rptOwnerZipCode>63105</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President &amp; CEO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-02-06</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>349650</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>MEH LLC</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-02-06</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>208030</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>454602</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>2009-02-06</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F2"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>165385</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>13.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>289217</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Meramec Enterprise Holdings, LLC (&quot;MEH&quot;) was dissolved and all shares of the issuers common stock held by MEH were distributed to the members of MEH without consideration, including the distribution of 208,030 shares to trusts established by the reporting person.</footnote>
        <footnote id="F2">Private sale.</footnote>
        <footnote id="F3">154,602 shares are held in a revocable trust of which the reporting person is settler and beneficiary.  These shares were previously reported as held indirectly through a trust.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Kevin Eichner</signatureName>
        <signatureDate>2009-02-06</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
