<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2004-09-28</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000866787</issuerCik>
        <issuerName>AUTOZONE INC</issuerName>
        <issuerTradingSymbol>AZO</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001126396</rptOwnerCik>
            <rptOwnerName>ESL INVESTMENTS INC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>200 GREENWICH AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>GREENWICH</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06830</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000923727</rptOwnerCik>
            <rptOwnerName>ESL PARTNERS LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>200 GREENWICH AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>GREENWICH</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06830</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000860585</rptOwnerCik>
            <rptOwnerName>RBS PARTNERS L P /CT</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>200 GREENWICH AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>GREENWICH</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06830</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001183200</rptOwnerCik>
            <rptOwnerName>LAMPERT EDWARD S</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1></rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity></rptOwnerCity>
            <rptOwnerState></rptOwnerState>
            <rptOwnerZipCode></rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2004-09-28</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>43000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>75.215</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>10576625</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2004-09-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>340000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>76.975</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>10916625</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>9653460</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnotes</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">These securities are owned by ESL Partners, L.P. (&quot;Partners&quot;).</footnote>
        <footnote id="F2">Includes (i) 3,683,037 shares held by ESL Investors, L.L.C. (&quot;Investors&quot;), (ii) 71,771 shares held by ESL Institutional Partners, L.P. (&quot;Institutional&quot;), (iii) 5,875,557 shares held by Acres Partners, L.P. (&quot;Acres&quot;), (iv) 19,310 shares held by ESL Investment Management, LLC (&quot;ESLIM&quot;) and (v) 3,785 shares held by Edward S. Lampert.</footnote>
        <footnote id="F3">This Form 4 is filed on behalf of Partners, ESL Investments, Inc. (&quot;Investments&quot;), RBS Partners, L.P. (&quot;RBS&quot;) and Edward S. Lampert. RBS is the general partner of Partners and the manager of Investors. Investments is the general partner of RBS and Acres. RBS Investment Management, LLC (&quot;RBSIM&quot;) is the general partner of Institutional. Mr. Lampert is a controlling stockholder of Investments and the managing member of ESLIM and RBSIM.</footnote>
        <footnote id="F4">Each of Partners, Institutional, Investors, Acres, ESLIM, Investments, RBS, RBSIM and Mr. Lampert may be deemed to be the beneficial owner of the securities reported herein. The total amount of securities reported as beneficially owned by Partners, Institutional, Investors, Acres and ESLIM is greater than Investments' or Mr. Lampert's indirect pecuniary interest in such securities. The total amount of securities reported as beneficially owned by Partners and Investors is greater than RBS' indirect pecuniary interest in such securities. The total amount of securities reported as beneficially owned by Institutional is greater than RBSIM's indirect pecuniary interest in such securities.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ William C. Crowley, for ESL Investments, Inc.</signatureName>
        <signatureDate>2004-09-30</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ William C. Crowley, for ESL Partners, L.P.</signatureName>
        <signatureDate>2004-09-30</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ William C. Crowley, for RBS Partners, L.P.</signatureName>
        <signatureDate>2004-09-30</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Edward S. Lampert</signatureName>
        <signatureDate>2004-09-30</signatureDate>
    </ownerSignature>
</ownershipDocument>

