<DOCUMENT>
<TYPE>EX-5
<SEQUENCE>2
<FILENAME>ex51.txt
<DESCRIPTION>LEGAL OPINION OF KRONISH LIEB WEINER & HELLMAN
<TEXT>
EXHIBIT 5.1



                                                        April 30, 2004

Research Frontiers Incorporated
240 Crossways Park Drive
Woodbury, New York 11797

Ladies and Gentlemen:

We have acted as special counsel to Research Frontiers
Incorporated, a Delaware corporation (the "Company"), in
connection with its Registration Statement on Form S-3 (the
"Registration Statement") under the Securities Act of 1933, as
amended (the "Act"), pertaining to the issuance by the Company
from time to time, together or separately, and as set forth in the
prospectus contained in the Registration Statement (the
"Prospectus") and in one or more supplements to the Prospectus
(each, a "Prospectus Supplement"), of up to 2,000,000 shares of
common stock, par value $.0001 per share, of the Company (the
"Common Stock") and/or warrants to purchase such Common Stock
(the "Warrants") at prices and on terms to be determined by market
conditions at the time of offering thereof.

In so acting, we have examined originals or copies,
certified or otherwise identified to our satisfaction, of the
Company's Restated Certificate of Incorporation (the "Certificate"),
the resolutions to be adopted by the Board of Directors of the
Company authorizing the filing of the Registration Statement and
such other corporate records, agreements, documents and other
instruments, and such certificates or comparable documents of
public officials and of officers and representatives of the Company,
and have made such inquiries of such officers and representatives,
as we have deemed relevant and necessary as a basis for the
opinions hereinafter set forth.

In such examination, we have assumed the genuineness of
all signatures, the legal capacity of natural persons, the authenticity
of all documents submitted to us as originals, the conformity to
original documents of all documents submitted to us as copies and
the authenticity of the originals of such latter documents.  As to all
questions of fact material to this opinion that have not been
independently established, we have relied upon certificates or
comparable documents of officers and representatives of the
Company.

Based on the foregoing, and subject to the qualifications
stated herein, we are of the opinion that:

1.   When (a) the Registration Statement (including any
post-effective amendments thereto) shall have become effective
under the Act, (b) a Prospectus Supplement describing the offered
securities shall have been filed with the Securities and Exchange
Commission ("SEC") and (c) shares of Common Stock shall have
been duly authorized pursuant to adoption by the Board of Directors
of the Company of one or more resolutions in form and content as
required by applicable law, and issued as contemplated by the
Registration Statement and/or the applicable Prospectus Supplement
and by such resolution(s), and assuming for the purpose of the
opinion set forth in this paragraph 1 that the Company shall have
sufficient authorized but unissued shares of Common Stock to so
issue such shares of Common Stock, such shares of Common Stock
will be validly issued, fully paid and non-assessable.

2.   The Warrants, when (a) the Registration Statement
(including any post-effective amendments thereto) shall have
become effective under the Act, (b) a Prospectus Supplement
describing the offered securities shall have been filed with the SEC
and (c) one or more agreements setting forth the terms of the
Warrants (the "Warrant Agreement") shall have been duly executed
and delivered by the parties thereto, (d) the Board of Directors shall
have taken all necessary corporate action in connection therewith,
including, without limitation, approving the terms of the Warrants
and reserving for issuance the shares of Common Stock underlying
the Warrants, (e) the Warrants shall have been executed and
authenticated in accordance with the terms of the Warrant
Agreement and (f) the Warrants shall have been issued, sold and
delivered in the manner and for the consideration stated in the
applicable definitive agreement approved by the Board of Directors,
the Warrants will be legal, valid and binding obligations of the
Company enforceable in accordance with their terms, subject to
applicable bankruptcy, insolvency, fraudulent conveyance,
reorganization, moratorium and similar laws affecting creditors'
rights and remedies generally, and subject, as to enforceability, to
general principles of equity, including principles of commercial
reasonableness, good faith and fair dealing (regardless of whether
enforcement is sought in a proceeding at law or in equity) and
except that rights to indemnification and contribution thereunder
and under the Warrant Agreement may be void or limited by federal
or state securities laws or public policy relating thereto.

To the extent that the obligations of the Company under
any Warrant Agreement may be dependent upon such matters, we
assume for purposes of the opinions set forth herein that each other
party to such Warrant Agreement is duly organized, validly existing
and in good standing under the laws of its jurisdiction of
organization; that each such party is duly qualified to engage in the
activities contemplated by each Warrant Agreement to which it is a
party; that each Warrant Agreement has been duly authorized,
executed and delivered by such other party thereto and constitutes
the legal, valid and binding obligation of such party, enforceable
against it in accordance with its terms; that each such party is in
compliance with all applicable laws and regulations relating thereto;
and that each such party has the requisite organizational and legal
power and authority to perform its obligations under each Warrant
Agreement to which it is a party.

The opinions expressed herein are limited to the laws of
the State of New York, the corporate laws of the State of Delaware,
and the federal laws of the United States, and we express no opinion
as to the effect on the matters covered by this letter of the laws of
any other jurisdiction.

The opinions expressed herein are rendered solely for
your benefit in connection with the transactions described herein.
Such opinions may not be used or relied upon by any other person,
nor may this letter or any copies thereof be furnished to a third
party, filed with a governmental agency, quoted, cited or otherwise
referred to without our prior written consent, except that we hereby
consent to the filing of this opinion as an exhibit to the Registration
Statement and to the reference to our Firm under the caption "Legal
Matters" in the Prospectus contained therein.

     Very truly yours,


    /s/  KRONISH, LIEB, WEINER & HELLMAN LLP

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