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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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 d5A8wdww5sT5t/dxoaxfVQ==

<SEC-DOCUMENT>0001140361-06-012693.txt : 20060830
<SEC-HEADER>0001140361-06-012693.hdr.sgml : 20060830
<ACCEPTANCE-DATETIME>20060830180253
ACCESSION NUMBER:		0001140361-06-012693
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20060830
FILED AS OF DATE:		20060830
DATE AS OF CHANGE:		20060830

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			SCHNEIDER HENRY/NY
		CENTRAL INDEX KEY:			0001121549

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-10238
		FILM NUMBER:		061066286

	MAIL ADDRESS:	
		STREET 1:		C/O ROBINSON BROG LEINAAND
		STREET 2:		1345 SIXTH AVE
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10105

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			U S ENERGY SYSTEMS INC
		CENTRAL INDEX KEY:			0000351917
		STANDARD INDUSTRIAL CLASSIFICATION:	ELECTRIC, GAS & SANITARY SERVICES [4900]
		IRS NUMBER:				521216347
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0609

	BUSINESS ADDRESS:	
		STREET 1:		545 MADISON AVENUE
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10022
		BUSINESS PHONE:		2125888901

	MAIL ADDRESS:	
		STREET 1:		545 MADISON AVENUE
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10022

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	U S ENVIROSYSTEMS INC /DE/
		DATE OF NAME CHANGE:	19960607

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	COGENIC ENERGY SYSTEMS INC
		DATE OF NAME CHANGE:	19940714
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2006-08-30</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000351917</issuerCik>
        <issuerName>U S ENERGY SYSTEMS INC</issuerName>
        <issuerTradingSymbol>USEY</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001121549</rptOwnerCik>
            <rptOwnerName>SCHNEIDER HENRY/NY</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O US ENERGY SYSTEMS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>545 MADISON AVENUE</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10022</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2006-08-30</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1400</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>3.99</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>218437</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2006-08-30</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>600</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>4</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>219037</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Henry N. Schneider</signatureName>
        <signatureDate>2006-08-30</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----