Exhibit No. 5.1

Writer's Direct Dial: (212) 225-2920
E-Mail: AKohn@cgsh.com
                                               July 19, 2005

Standard Microsystems Corporation
80 Arkay Drive
Hauppauge, New York 11788

Re: Standard Microsystems Corporation Registration Statement on Form S-8


Ladies and Gentlemen:

                  We have acted as counsel to Standard Microsystems Corporation,
a Delaware  corporation  (the  "Company"),  in  connection  with a  registration
statement on Form S-8 (the "Registration  Statement") to be filed today with the
Securities and Exchange Commission (the "Commission") pursuant to the Securities
Act of 1933, as amended (the "Act"), for the registration of 1,910,000 shares of
the Company's  common  stock,  par value $0.10 per share (the  "Shares"),  to be
issued under the Company's 2005  Inducement  Stock Option and  Restricted  Stock
Plan and the Company's  2004  Inducement  Stock Option Plan  (collectively,  the
"Plans"), and the related Series A Participating Preferred Stock purchase rights
(the  "Rights")  to be issued  pursuant  to the Rights  Agreement  (the  "Rights
Agreement")  dated as of January 7, 1998,  between  the  Company  and the Rights
Agent named  therein,  as amended by Amendment No. 1 dated January 23, 2001, and
as further amended by Amendment No. 2 dated April 9, 2002.

                  We have  participated in the  preparation of the  Registration
Statement  and have  reviewed  the  originals  or copies  certified or otherwise
identified to our satisfaction of all such corporate  records of the Company and
such other instruments and other certificates of public officials,  officers and
representatives  of the  Company and such other  persons,  and we have made such
investigations of law, as we have deemed appropriate as a basis for the opinions
expressed  below.  We have further  received a letter dated July 18, 2005,  from
George Houseweart,  General Counsel of the Company,  representing to us that the
Company has available for issuance a sufficient  number of authorized  shares to
deliver the Shares under the Plans, and are relying on such representation.

                  In rendering the opinions expressed below, we have assumed the
authenticity of all documents submitted to us as originals and the conformity to
the originals of all documents  submitted to us as copies. In addition,  we have
assumed  and have not  verified  the  accuracy  as to  factual  matters  of each
document we have reviewed.

                  Based on the foregoing, and subject to the further assumptions
and qualifications set forth below, it is our opinion that:

                  1. The  Shares  have been  duly  authorized  by all  necessary
corporate action of the Company and, when issued in accordance with the terms of
the Plans, at prices in excess of the par value thereof, will be validly issued,
fully paid and nonassessable.

                  2. Upon issuance of the Shares in accordance with the terms of
the Plans, at prices in excess of the par value thereof,  the Rights  associated
with the Shares will be validly issued.

                  The foregoing opinions are limited to the General  Corporation
Law of the State of Delaware.

                  We hereby  consent to the filing of this opinion as an exhibit
to the Registration  Statement.  In giving such consent, we do not thereby admit
that we are "experts" within the meaning of the Act or the rules and regulations
of the Commission issued thereunder with respect to any part of the Registration
Statement, including this exhibit.



                                            Very truly yours,

                                            CLEARY GOTTLIEB STEEN & HAMILTON LLP


                                            By:  /s/ Arthur H. Kohn
                                                 -------------------------------
                                                 Arthur H. Kohn, a partner