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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2017-07-05</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000101295</issuerCik>
        <issuerName>UNITED GUARDIAN INC</issuerName>
        <issuerTradingSymbol>UG</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000943504</rptOwnerCik>
            <rptOwnerName>GLOBUS KENNETH H</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O UNITED-GUARDIAN, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>230 MARCUS BLVD., P.O. BOX 18050</rptOwnerStreet2>
            <rptOwnerCity>HAUPPAUGE</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>11788</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2017-07-05</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>G</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>6700</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1377293</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">After the transfer of the 6,700 shares being gifted, Direct ownership is 308,647 shares, and indirect ownership is 1,068,646 shares. Of the shares owned indirectly, 308,646 shares are owned by wife, and 760,000 shares are under my voting control as co-trustee of the Alfred R. Globus Testamentary Trust</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Ken Globus</signatureName>
        <signatureDate>2017-07-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0306
4
2017-07-05
0
0000101295
UNITED GUARDIAN INC
UG
0000943504
GLOBUS KENNETH H
C/O UNITED-GUARDIAN, INC.
230 MARCUS BLVD., P.O. BOX 18050
HAUPPAUGE
NY
11788
1
1
1
0
President
Common Stock
2017-07-05
4
G
0
6700
0
D
1377293
D
After the transfer of the 6,700 shares being gifted, Direct ownership is 308,647 shares, and indirect ownership is 1,068,646 shares. Of the shares owned indirectly, 308,646 shares are owned by wife, and 760,000 shares are under my voting control as co-trustee of the Alfred R. Globus Testamentary Trust
/s/ Ken Globus
2017-07-05