<SUBMISSION>
<ACCESSION-NUMBER>0000893538-05-000038
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20050315
<FILING-DATE>20050317
<DATE-OF-FILING-DATE-CHANGE>20050317
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>ST MARY LAND & EXPLORATION CO
<CIK>0000893538
<ASSIGNED-SIC>1311
<IRS-NUMBER>410518430
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>1776 LINCOLN ST STE 700
<CITY>DENVER
<STATE>CO
<ZIP>80203
<PHONE>303-861-8140
</BUSINESS-ADDRESS>
</ISSUER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>WILLSON KEVIN E
<CIK>0001277437
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-31539
<FILM-NUMBER>05688901
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>C/O ST MARY LAND & EXPLORATION
<STREET2>580 WESTLAKE PARK BLVD #600
<CITY>HOUSTON
<STATE>TX
<ZIP>77079
<PHONE>9184887600
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>C/O ST MARY LAND & EXPLORATION
<STREET2>7060 S. YALE #800
<CITY>TULSA
<STATE>OK
<ZIP>74136
</MAIL-ADDRESS>
<FORMER-NAME>
<FORMER-CONFORMED-NAME>WILSON KEVIN E
<DATE-CHANGED>20040126
</FORMER-NAME>
</REPORTING-OWNER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-03-15</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000893538</issuerCik>
        <issuerName>ST MARY LAND &amp; EXPLORATION CO</issuerName>
        <issuerTradingSymbol>SM</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001277437</rptOwnerCik>
            <rptOwnerName>WILLSON KEVIN E</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O ST MARY LAND &amp; EXPLORATION</rptOwnerStreet1>
            <rptOwnerStreet2>7060 S. YALE #800</rptOwnerStreet2>
            <rptOwnerCity>TULSA</rptOwnerCity>
            <rptOwnerState>OK</rptOwnerState>
            <rptOwnerZipCode>74136</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Sr.VP-MidContinent Drlg &amp; Prdc</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Restricted Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2005-03-17</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>758</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock; $.01 Par Value</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>758</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>8968</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Each restricted stock unit represents a contingent right to receive one share of SM Common Stock.</footnote>
        <footnote id="F2">The restricted stock units vest in four equal installments beginning March 15, 2005. Vested shares will be issued to the reporting person on March 15, 2008, at which time all restrictions lapse.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>James C. Robertson (Attorney-In-Fact)</signatureName>
        <signatureDate>2005-03-17</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
