-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
 MFgwCgYEVQgBAQICAf8DSgAwRwJAW2sNKK9AVtBzYZmr6aGjlWyK3XmZv3dTINen
 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 K3RFMsYSwXpwe+rw4i/l8Om0tsSRVxZoLgjTGrI8XQRfRRQeVB+mrgek0TM1v51J
 V8xwolrkOxFSM0b4BW4uAQ==

<SEC-DOCUMENT>0001023459-04-000005.txt : 20041214
<SEC-HEADER>0001023459-04-000005.hdr.sgml : 20041214
<ACCEPTANCE-DATETIME>20041214164402
ACCESSION NUMBER:		0001023459-04-000005
CONFORMED SUBMISSION TYPE:	4/A
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20040416
FILED AS OF DATE:		20041214
DATE AS OF CHANGE:		20041214

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			DAHLEN JEFFREY A
		CENTRAL INDEX KEY:			0001258351

	FILING VALUES:
		FORM TYPE:		4/A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-32046
		FILM NUMBER:		041201953

	BUSINESS ADDRESS:	
		STREET 1:		1220 W. AVE. J
		CITY:			LANCASTER
		STATE:			CA
		ZIP:			93534

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			SIMULATIONS PLUS INC
		CENTRAL INDEX KEY:			0001023459
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-COMPUTER INTEGRATED SYSTEMS DESIGN [7373]
		IRS NUMBER:				954595609
		FISCAL YEAR END:			0831

	BUSINESS ADDRESS:	
		STREET 1:		1220 W. AVENUE J
		STREET 2:		*
		CITY:			LANCASTER
		STATE:			CA
		ZIP:			93534-2902
		BUSINESS PHONE:		661-723-7723

	MAIL ADDRESS:	
		STREET 1:		1220 W. AVENUE J
		CITY:			LANCASTER
		STATE:			CA
		ZIP:			93534-2902
</SEC-HEADER>
<DOCUMENT>
<TYPE>4/A
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2004-04-16</periodOfReport>

    <dateOfOriginalSubmission>2004-04-22</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001023459</issuerCik>
        <issuerName>SIMULATIONS PLUS INC</issuerName>
        <issuerTradingSymbol>SLP</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001258351</rptOwnerCik>
            <rptOwnerName>DAHLEN JEFFREY A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1220 W. AVENUE J</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>LANCASTER</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>93534</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>V.P., Research &amp; Development</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Simulations Plus, Inc. stock option</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>4.6</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2004-04-16</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>50000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>4.6</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2005-04-16</value>
            </exerciseDate>
            <expirationDate>
                <value>2014-04-16</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Simulations Plus, Inc. common stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>50000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>50000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <remarks>Corrects errors in earlier Form 4 and Form 4A filings for this transaction,  Initial transaction was reported as securities instead of derivative securities.</remarks>

    <ownerSignature>
        <signatureName>Jeffrey A. Dahlen</signatureName>
        <signatureDate>2004-12-14</signatureDate>
    </ownerSignature>
</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----