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

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-01-25</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000055362</issuerCik>
        <issuerName>KENTUCKY INVESTORS INC</issuerName>
        <issuerTradingSymbol>kinv</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001223520</rptOwnerCik>
            <rptOwnerName>TAP &amp; CO</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>P O BOX 717</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>FRANKFORT</rptOwnerCity>
            <rptOwnerState>KY</rptOwnerState>
            <rptOwnerZipCode>40602</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>Benefit Plan Trustee/Group (1)</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2005-01-25</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>861</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>23.94</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>0</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>273505.96</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">N/A</footnote>
        <footnote id="F2">N/A</footnote>
    </footnotes>

    <remarks>(1) Explanation of the Group are Investors Heritage Life Insurance Company, Investors Underwriters, Inc., HLW Investment Corp., TAP &amp; CO., Harry Lee Waterfield II, RoseGayle Waterfield Hardy, Nancy Waterfield Walton, HLW Corporation, Harry Lee Waterfield II, RoseGayle Waterfield Hardy, Nancy Waterfield Walton Trust Funds 1, 2, 3 and 4 and RoseGayle Waterfield Hardy, Nancy Waterfield Walton, Harry Lee Waterfield II Trust dated 12-22-1976 and Kentucky Investors, Inc. Employee Retirement Plan.</remarks>

    <ownerSignature>
        <signatureName>Jane S. Jackson, Secretary of Kentucky Investors, Inc., on behalf of TAP &amp; CO.</signatureName>
        <signatureDate>2005-01-26</signatureDate>
    </ownerSignature>
</ownershipDocument>

