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

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-04-22</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000944380</rptOwnerCik>
            <rptOwnerName>GLOBUS ALFRED R</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>Chief Executive Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2005-04-22</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>G</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>39000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1268240</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">In addition to the direct ownership stated here there is also the following indirect ownership: (a) 14,966 shares owned by the Foundation For Science &amp; Theology, of which Alfred Globus is a director; (b) 23,500 shares owned by Alfred Globus' wife; and 120 shares held as guardian for Jeffrey Globus.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Alfred R. Globus by Ken Globus, Attorney-in-fact</signatureName>
        <signatureDate>2005-04-26</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0202
4
2005-04-22
0
0000101295
UNITED GUARDIAN INC
UG
0000944380
GLOBUS ALFRED R
C/O UNITED-GUARDIAN, INC.
230 MARCUS BLVD., P.O. BOX 18050
HAUPPAUGE
NY
11788
1
1
1
0
Chief Executive Officer
Common Stock
2005-04-22
4
G
0
39000
0
D
1268240
D
In addition to the direct ownership stated here there is also the following indirect ownership: (a) 14,966 shares owned by the Foundation For Science & Theology, of which Alfred Globus is a director; (b) 23,500 shares owned by Alfred Globus' wife; and 120 shares held as guardian for Jeffrey Globus.
Alfred R. Globus by Ken Globus, Attorney-in-fact
2005-04-26