<?xml version="1.0"?>

<ownershipDocument>

    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2003-09-12</periodOfReport>


    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001133932</issuerCik>
        <issuerName>TREK RESOURCES INC</issuerName>
        <issuerTradingSymbol>TREK</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001166450</rptOwnerCik>
            <rptOwnerName>MONTGOMERY MICHAEL E</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>4925 GREENVILLE AVE</rptOwnerStreet1>
            <rptOwnerStreet2>STE 955</rptOwnerStreet2>
            <rptOwnerCity>DALLAS</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>75206</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President, CEO, CFO &amp; COB</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>

        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $.10 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2003-09-12</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>35864</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.71</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2097972</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>

    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The reporting person acquired the shares of common stock reported herein in exchange for the cancellation of a promissory note of the seller of such shares in the principal amount of $25,104.80 that was payable to the order of the reporting persion.  On the date of purchase, approximately $317.77 of accrued but unpaid interest was due to the reporting person under such promissory note.  Accordingly, the reporting person cancelled obligations totaling $25,422.57 (approximately $0.71 per share) in exchange for such shares of common stock.</footnote>
    </footnotes>


    <ownerSignature>
        <signatureName>Michael E. Montgomery</signatureName>
        <signatureDate>2003-09-15</signatureDate>
    </ownerSignature>

</ownershipDocument>

