1
                                                                     EXHIBIT 3.1



                           CERTIFICATE OF AMENDMENT OF
                           FOURTH AMENDED AND RESTATED
                          CERTIFICATE OF INCORPORATION
                                OF SYNOPSYS, INC.

        SYNOPSYS, INC., a corporation organized and existing under and by virtue
of the General Corporation Law of the State of Delaware (the "Corporation"),
DOES HEREBY CERTIFY:

        FIRST: That the Board of Directors of the Corporation approved a
resolution by unanimous written consent to amend Article IV.A of the Fourth
Amended and Restated Certificate of Incorporation of the Corporation to read in
its entirety as follows:

        "A. Classes of Stock. This Corporation is authorized to issue two
        classes of stock to be designated, respectively, as "Common Stock" and
        "Preferred Stock." The total number of shares that the Corporation is
        authorized to issue is Four Hundred Two Million (402,000,000), par value
        of one cent ($.01) per share. Four Hundred Million (400,000,000) shares
        shall be Common Stock and Two Million (2,000,000) shares shall be
        Preferred Stock."

        SECOND: The Annual Meeting of Stockholders of the Corporation was duly
called and held on March 3, 2000 in accordance with Section 222 of the General
Corporation law of the State of Delaware at which meeting a majority of the
outstanding shares of the Corporation were voted in favor of the proposed
amendment.

        THIRD: That said amendment was duly adopted by the Board of Directors
and stockholders of the Corporation in accordance with the provisions of Section
242 of the General Corporation Law of the State of Delaware.

        IN WITNESS WHEREOF, the Corporation has caused this certificate to be
signed on its behalf by the undersigned duly authorized officer of the
Corporation on this 13th day of March, 2000.


                                                   /s/ Roger Klein
                                                   -----------------------------
                                                   Roger Klein
                                                   Assistant Secretary



                                       23