-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
 MFgwCgYEVQgBAQICAf8DSgAwRwJAW2sNKK9AVtBzYZmr6aGjlWyK3XmZv3dTINen
 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 ERHqlfkqxkQXdL8zITDC69pgEkVdBEHwVqrL4mKRv3MK7YqnFRvVOycvQHExV9XL
 jxbLQXNtsouwAlpAPz9utg==

<SEC-DOCUMENT>0000074208-04-000047.txt : 20041215
<SEC-HEADER>0000074208-04-000047.hdr.sgml : 20041215
<ACCEPTANCE-DATETIME>20041215163524
ACCESSION NUMBER:		0000074208-04-000047
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20041213
FILED AS OF DATE:		20041215
DATE AS OF CHANGE:		20041215

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			CARLIN MARTHA R
		CENTRAL INDEX KEY:			0001195699

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-10524
		FILM NUMBER:		041205227

	BUSINESS ADDRESS:	
		STREET 1:		UNITED DOMINION REALTY TRUST INC
		CITY:			HIGHLANDS RANCH
		STATE:			CO
		ZIP:			80129

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			UNITED DOMINION REALTY TRUST INC
		CENTRAL INDEX KEY:			0000074208
		STANDARD INDUSTRIAL CLASSIFICATION:	REAL ESTATE INVESTMENT TRUSTS [6798]
		IRS NUMBER:				540857512
		STATE OF INCORPORATION:			MD
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		400 EAST CARY STREET
		CITY:			RICHMOND
		STATE:			VA
		ZIP:			23219-3802
		BUSINESS PHONE:		8047802691

	MAIL ADDRESS:	
		STREET 1:		400 EAST CARY STREET
		CITY:			RICHMOND
		STATE:			VA
		ZIP:			23219-3802

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	OLD DOMINION REAL ESTATE INVESTMENT TRUST
		DATE OF NAME CHANGE:	19850110

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	OLD DOMINION REIT ONE
		DATE OF NAME CHANGE:	19770921

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	OLD DOMINION REAL ESTATE INVESTMENT TRUS
		DATE OF NAME CHANGE:	19741216
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>c0001195699d20041215f4f.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2004-12-13</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000074208</issuerCik>
        <issuerName>UNITED DOMINION REALTY TRUST INC</issuerName>
        <issuerTradingSymbol>UDR</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001195699</rptOwnerCik>
            <rptOwnerName>CARLIN MARTHA R</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>400 EAST CARY STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>RICHMOND</rptOwnerCity>
            <rptOwnerState>VA</rptOwnerState>
            <rptOwnerZipCode>23219</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Senior Vice President</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2004-12-13</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>G</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>914</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>31942</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2004-12-13</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>G</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>914</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>914</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Husband</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Gift to husband.  The reporting person disclaims beneficial ownership of the shares held by her husband, and this report should not be deemed an admission that the reporting person is the beneficial owner of her husband's shares for purposes of section 16 or for any other purpose.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>MARTHA R CARLIN</signatureName>
        <signatureDate>2004-12-15</signatureDate>
    </ownerSignature>
</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----
