Exhibit 5.1

Pepper Hamilton LLP
Attorneys at Law
3000 Two Logan Square
Eighteenth and Arch Streets
Philadelphia, PA 19103-2799
215-981-4000
Fax 215-981-4750

                                May 24, 2001


Integrated Circuit Systems, Inc.
2435 Boulevard of the Generals
Norristown, PA 19403

          Re:  Registration Statement on Form S-3

Ladies and Gentlemen:

          We have acted as counsel to Integrated Circuit Systems, Inc., a
Pennsylvania corporation (the "Company"), in connection with the registration
under the Securities Act of 1933, as amended (the "Act"), of a secondary
offering (the "Offering") of up to 12,600,000 shares (including 1,350,000 shares
subject to the underwriters' over-allotment option) (the "Shares") of the
Company's Common Stock, par value $.01 per share (the "Common Stock") to be
offered by certain selling shareholders of the Company (the "Selling
Shareholders").


          The opinion is delivered in accordance with the requirements of Item
601(b)(5) of Regulation S-K under the Act.

          We have examined originals or copies, certified or otherwise
identified to our satisfaction, of (i) the Registration Statement on Form S-3
filed under the Act with the Securities and Exchange Commission (the
"Commission") on May 11, 2001; (ii) Amendment No. 1 to the Registration
Statement filed under the Act with the Commission on May 15, 2001, (iii)
Amendment No. 2 to the Registration Statement filed under the Act on May 24,
2001, (iv) the Registration Statement on Form S-3 filed in accordance with Rule
462(b) under the Act with the Commission on May 24, 2001, (v) the form of
underwriting agreement, filed as Exhibit 1.1 to Amendment No. 1 to the
Registration Statement (the "Underwriting Agreement"), to be entered into by and
among the Company and representatives of the several underwriters; (vi) the form
of the Company's Amended, and Restated Articles of Incorporation and By-Laws as
currently in effect; (vii) certain resolutions of the Board of Directors of the
Company relating to, among other things, the transactions giving rise to the
issuance of the Shares; and (viii) such other documents as we have deemed
necessary or appropriate as a basis for the opinions set forth below.
          In our examination, we have assumed the legal capacity of all natural
persons, the genuineness of all signatures, the authenticity of all documents
submitted to us as certified or photostatic copies and the authenticity of the
originals of such latter documents.  As to any facts material to the opinions
expressed herein which were not independently established or verified, we have
relied upon statements and representations of officers and other representatives
of the Company and others.



Integrated Circuit Systems, Inc.
May 24, 2001

Page 2


          We express no opinion as to the laws of any other jurisdiction other
than the Federal laws of the United States of America and the Business
Corporation Law of the Commonwealth of Pennsylvania.

          Based upon and subject to the foregoing, we are of the opinion that
the Shares are duly authorized, validly issued, fully paid and nonassessable.

          We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement and to the reference to this firm under the caption
"Legal Opinions" in the prospectus filed as part of the Registration Statement.
In giving such consent, we do not thereby admit that we are in the category of
persons whose consent is required under Section 7 of the Act or the Rules and
Regulations promulgated thereunder.

          This opinion is furnished by us, as your counsel, in connection with
the filing of the Registration Statement and, except as provided in the
immediately preceding paragraph, is not to be used, circulated, quoted or
otherwise referred to for any other purpose without our express written
permission or relied upon by any other person.

                                      Very truly yours,

                                      /s/ PEPPER HAMILTON LLP

                                      PEPPER HAMILTON LLP