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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 S9p0ov8cN/8x/pfLpf3AZyB2eYOb2hLb1j+z0xr7UsDqtL4YEeeubukUlAthXmrr
 GmUrS7tTYo9BvyEKZmiPEg==

<SEC-DOCUMENT>0001179477-03-000035.txt : 20030618
<SEC-HEADER>0001179477-03-000035.hdr.sgml : 20030618
<ACCEPTANCE-DATETIME>20030618122603
ACCESSION NUMBER:		0001179477-03-000035
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20030616
FILED AS OF DATE:		20030618

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			CASH R D
		CENTRAL INDEX KEY:			0001179477

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-08796
		FILM NUMBER:		03748380

	BUSINESS ADDRESS:	
		STREET 1:		180 EAST 100 SOUTH
		STREET 2:		PO BOX 45433
		CITY:			SALT LAKE CITY
		STATE:			UT
		ZIP:			84145-0433
		BUSINESS PHONE:		8013245205

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			QUESTAR CORP
		CENTRAL INDEX KEY:			0000751652
		STANDARD INDUSTRIAL CLASSIFICATION:	NATURAL GAS TRANSMISSION & DISTRIBUTION [4923]
		IRS NUMBER:				870407509
		STATE OF INCORPORATION:			UT
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		180 EAST 100 SOUTH ST
		STREET 2:		PO BOX 45433
		CITY:			SALT LAKE CITY
		STATE:			UT
		ZIP:			84145
		BUSINESS PHONE:		8015345000

	MAIL ADDRESS:	
		STREET 1:		180 EAST 100 SOUTH ST
		STREET 2:		P O BOX 45433
		CITY:			SALT LAKE CITY
		STATE:			UT
		ZIP:			84145
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>

<ownershipDocument>

    <documentType>4</documentType>

    <periodOfReport>2003-06-16</periodOfReport>


    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000751652</issuerCik>
        <issuerName>QUESTAR CORP</issuerName>
        <issuerTradingSymbol>STR</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001179477</rptOwnerCik>
            <rptOwnerName>CASH R D</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeSecurity>
        <securityTitle>
            <value>Phantom Stock Units</value>
        </securityTitle>
        <conversionOrExercisePrice>
            <value>34</value>
        </conversionOrExercisePrice>
        <transactionDate>
            <value>2003-06-16</value>
        </transactionDate>
        <transactionCoding>
            <transactionFormType>4</transactionFormType>
            <transactionCode>A</transactionCode>
            <equitySwapInvolved>0</equitySwapInvolved>
        </transactionCoding>
        <transactionTimeliness>
            <value></value>
        </transactionTimeliness>
        <transactionAmounts>
            <transactionShares>
                <value>106.0806</value>
            </transactionShares>
            <transactionValue>
                <value>34</value>
            </transactionValue>
            <transactionAcquiredDisposedCode>
                <value>A</value>
            </transactionAcquiredDisposedCode>
        </transactionAmounts>
        <exerciseDate>
            <value>1988-08-08</value>
        </exerciseDate>
        <expirationDate>
            <value>1988-08-08</value>
        </expirationDate>
        <underlyingSecurity>
            <underlyingSecurityTitle>
                <value>Phantom Stock Units</value>
            </underlyingSecurityTitle>
            <underlyingSecurityShares>
                <value>106.0806</value>
            </underlyingSecurityShares>
        </underlyingSecurity>
        <postTransactionAmounts>
            <sharesOwnedFollowingTransaction>
                <value>55710.1258</value>
                <footnoteId id="F1"/>
            </sharesOwnedFollowingTransaction>
        </postTransactionAmounts>
        <ownershipNature>
            <directOrIndirectOwnership>
                <value>D</value>
            </directOrIndirectOwnership>
        </ownershipNature>
    </derivativeSecurity>

    <footnotes>
        <footnote id="F1">This total includes 36,108.1141 units held in an excess benefits plan.  This total does not include 6,936 shares held indirectly through family trusts,52,873 shares held indirectly in a private foundation, 289,739 Common Stock shares, and 759,761 vested Stock Options.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Connie C. Holbrook Attorney in Fact for R.D. Cash</signatureName>
        <signatureDate>2003-06-18</signatureDate>
    </ownerSignature>

</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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