-----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,
 TvzyfIhZcxN0HffTGn15iKho7Lb2buNbHv3OzurolTjQOpIbT9LIVFxBpt1bQAU6
 UVDPkTmelo2Y1VbTlplIyA==

<SEC-DOCUMENT>0001140361-09-014016.txt : 20090604
<SEC-HEADER>0001140361-09-014016.hdr.sgml : 20090604
<ACCEPTANCE-DATETIME>20090604170504
ACCESSION NUMBER:		0001140361-09-014016
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20090602
FILED AS OF DATE:		20090604
DATE AS OF CHANGE:		20090604

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			CAVAZZA CLAUDIO
		CENTRAL INDEX KEY:			0001164803

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-15070
		FILM NUMBER:		09874721

	MAIL ADDRESS:	
		STREET 1:		VIA SUDAFRICA 20
		CITY:			ROME ITALY
		STATE:			L6
		ZIP:			00000

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			REGENERX BIOPHARMACEUTICALS INC
		CENTRAL INDEX KEY:			0000707511
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				521253406
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		3 BETHESDA METRO CENTER
		STREET 2:		SUITE 700
		CITY:			BETHESDA
		STATE:			MD
		ZIP:			20814
		BUSINESS PHONE:		3019611992

	MAIL ADDRESS:	
		STREET 1:		3 BETHESDA METRO CENTER
		STREET 2:		SUITE 700
		CITY:			BETHESDA
		STATE:			MD
		ZIP:			20814

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	ALPHA 1 BIOMEDICALS INC
		DATE OF NAME CHANGE:	19950719
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2009-06-02</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000707511</issuerCik>
        <issuerName>REGENERX BIOPHARMACEUTICALS INC</issuerName>
        <issuerTradingSymbol>RGN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001164803</rptOwnerCik>
            <rptOwnerName>CAVAZZA CLAUDIO</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>VIA SUDAFRICA, 20</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>ROME</rptOwnerCity>
            <rptOwnerState>L6</rptOwnerState>
            <rptOwnerZipCode>00000</rptOwnerZipCode>
            <rptOwnerStateDescription>ITALY</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-06-02</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>312500</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>.40</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5052582</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F3"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Indirect</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">1,034,482 of these shares  were acquired on December 10, 2008 pursuant to a purchase agreement with the Issuer that provides that the Issuer, rather than Inverlochy Consultadoria e Servicos Lda (?Inverlochy?), has all voting rights in respect of the shares through December 31, 2011, and that Inverlochy may not transfer the shares through December 31, 2011 except for transfers to Affiliates (as defined therein).  2,500,000 of these shares were acquired on February 29, 2008 pursuant to a purchase agreement with the Issuer that provides that the Issuer shall have the right to repurchase the shares at any time until December 31, 2009, for $2.00 per share, or at any time between January 1, 2010, and December 31, 2010, for $2.50 per share.</footnote>
        <footnote id="F2">Furthermore, the purchase agreement provides that the Issuer, rather than Inverlochy, has all voting rights in respect of the shares through December 31, 2010, and that Inverlochy may not transfer the shares  through December 31, 2010 except for transfers to Affiliates (as defined therein).</footnote>
        <footnote id="F3">Securities directly owned by Inverlochy. Claudio Cavazza indirectly owns 100% of Inverlochy.</footnote>
    </footnotes>

    <remarks>Exhibit List:  Exhibit 24-Power of Attorney</remarks>

    <ownerSignature>
        <signatureName>/s/ Nicola Wullschleger (Attorney-in-Fact)</signatureName>
        <signatureDate>2009-06-04</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----