-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
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MIC-Info: RSA-MD5,RSA,
 GTT5URYQoClvDaM3dlaNLd0bIfW3Ci+1LLjLDz6zQkc3BrEhT3unxAUUoKsKH2Zh
 nO5gmIWrtfxSl/XVdZvXkA==

<SEC-DOCUMENT>0000939675-05-000006.txt : 20050408
<SEC-HEADER>0000939675-05-000006.hdr.sgml : 20050408
<ACCEPTANCE-DATETIME>20050408100749
ACCESSION NUMBER:		0000939675-05-000006
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20050329
FILED AS OF DATE:		20050408
DATE AS OF CHANGE:		20050408

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			SCIENTIFIC INDUSTRIES INC
		CENTRAL INDEX KEY:			0000087802
		STANDARD INDUSTRIAL CLASSIFICATION:	LABORATORY ANALYTICAL INSTRUMENTS [3826]
		IRS NUMBER:				042217279
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0630

	BUSINESS ADDRESS:	
		STREET 1:		70 ORVILLE DR
		STREET 2:		AIRPORT INTERNATIONAL PLZ
		CITY:			BOHEMIA
		STATE:			NY
		ZIP:			11716
		BUSINESS PHONE:		5165674700

	MAIL ADDRESS:	
		STREET 1:		70 ORVILLE DR
		CITY:			BOHEMIA
		STATE:			NY
		ZIP:			11716

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			KNOWLES ROGER B
		CENTRAL INDEX KEY:			0000939675

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-06658
		FILM NUMBER:		05740488

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		6315674700

	MAIL ADDRESS:	
		STREET 1:		C/O SCIENTIFIC INDUSTRIES INC
		STREET 2:		70 ORVILLE DR
		CITY:			BOHEMIA
		STATE:			NY
		ZIP:			11716
</SEC-HEADER>
<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>2005-03-29</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000087802</issuerCik>
        <issuerName>SCIENTIFIC INDUSTRIES INC</issuerName>
        <issuerTradingSymbol>SCND</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000939675</rptOwnerCik>
            <rptOwnerName>KNOWLES ROGER B</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O SCIENTIFIC INDUSTRIES INC</rptOwnerStreet1>
            <rptOwnerStreet2>70 ORVILLE DR</rptOwnerStreet2>
            <rptOwnerCity>BOHEMIA</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>11716</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Scientific Industries, Inc. Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2005-03-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>500</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.9</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>67995</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <ownerSignature>
        <signatureName>Roger B. Knowles</signatureName>
        <signatureDate>2005-04-08</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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