-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 SWjD7/b0/Zl8TWleWWJ4Lfwy0GZ114rVY/ZZJ0Bnc5C9h2e0uVjpCY4upGN8WevR
 kAkrs78G5sTMRcRFCF0tFQ==

<SEC-DOCUMENT>0001179110-05-022867.txt : 20051213
<SEC-HEADER>0001179110-05-022867.hdr.sgml : 20051213
<ACCEPTANCE-DATETIME>20051213143518
ACCESSION NUMBER:		0001179110-05-022867
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20051212
FILED AS OF DATE:		20051213
DATE AS OF CHANGE:		20051213

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			MONTGOMERY SCOTT A
		CENTRAL INDEX KEY:			0001258734

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-13015
		FILM NUMBER:		051260690

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		310 282 6793

	MAIL ADDRESS:	
		STREET 1:		1840 CENTURY PARK EAST
		CITY:			LOS ANGELES
		STATE:			CA
		ZIP:			90067

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			NATIONAL MERCANTILE BANCORP
		CENTRAL INDEX KEY:			0000714801
		STANDARD INDUSTRIAL CLASSIFICATION:	STATE COMMERCIAL BANKS [6022]
		IRS NUMBER:				953819685
		STATE OF INCORPORATION:			CA
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		1840 CENTURY PARK EAST
		CITY:			LOS ANGELES
		STATE:			CA
		ZIP:			90067
		BUSINESS PHONE:		3102772265

	MAIL ADDRESS:	
		STREET 1:		1840 CENTURY PARK EAST
		CITY:			LOS ANGELES
		STATE:			CA
		ZIP:			90067
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4 -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-12-12</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000714801</issuerCik>
        <issuerName>NATIONAL MERCANTILE BANCORP</issuerName>
        <issuerTradingSymbol>MBLA</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001258734</rptOwnerCik>
            <rptOwnerName>MONTGOMERY SCOTT A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1880 CENTURY PARK E STE. 800</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>LOS ANGELES</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>90067</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President/CEO</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock NPV</value>
            </securityTitle>
            <transactionDate>
                <value>2005-12-12</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>G</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1350</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>19</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>98288</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Charitable donation to St. Monica's Catholic Church, Archdiocese of Los Angeles, California</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Scott A. Montgomery</signatureName>
        <signatureDate>2005-12-13</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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