SCHEDULE 14A INFORMATION

               PROXY STATEMENT PURSUANT TO SECTION 14(A) OF THE
                       SECURITIES EXCHANGE ACT OF 1934 
                               (AMENDMENT NO.  )
        
Filed by the Registrant [X]

Filed by a Party other than the Registrant [_] 

Check the appropriate box:

[_]  Preliminary Proxy Statement        [_]  CONFIDENTIAL, FOR USE OF THE    
                                             COMMISSION ONLY (AS PERMITTED BY
[_]  Definitive Proxy Statement              RULE 14a-6(e)(2))
                                                                               
[X]  Definitive Additional Materials                                            
                                                                               
[_]  Soliciting Material Pursuant to Section 240.14a-11(c) or Section 240.14a-12
                                                                                


                        Quickturn Design Systems, Inc.
   ------------------------------------------------------------------------
               (Name of Registrant as Specified In Its Charter)            
                                                                           
                                                                           
   ------------------------------------------------------------------------
   (Name of Person(s) Filing Proxy Statement, if other than the Registrant)

   
Payment of Filing Fee (Check the appropriate box):

[X]  No fee required.

[_]  Fee computed on table below per Exchange Act Rules 14a-6(i)(4) and 0-11.

     (1) Title of each class of securities to which transaction applies:

     (2) Aggregate number of securities to which transaction applies:

     (3) Per unit price or other underlying value of transaction computed
         pursuant to Exchange Act Rule 0-11 (Set forth the amount on which
         the filing fee is calculated and state how it was determined):

     (4) Proposed maximum aggregate value of transaction:

     (5) Total fee paid:

[_]  Fee paid previously with preliminary materials.
     
[_]  Check box if any part of the fee is offset as provided by Exchange Act
     Rule 0-11(a)(2) and identify the filing for which the offsetting fee was 
     paid previously. Identify the previous filing by registration statement 
     number, or the Form or Schedule and the date of its filing.

     (1) Amount Previously Paid:
 
     (2) Form, Schedule or Registration Statement No.:

     (3) Filing Party:
      
     (4) Date Filed:

Notes:



[QUICKTURN LOGO APPEARS HERE]                                     EXHIBIT 50
 
Contacts:
     QUICKTURN DESIGN SYSTEMS, INC.                    Abernathy MacGregor Frank
     Joan Powell                                       Pauline Yoshihashi
     Director, Marketing Communications                (213) 630-6550
     (408) 914-6000                                    Matt Sherman
     joan@quickturn.com                                (212) 371-5999


FOR IMMEDIATE RELEASE


            MENTOR GRAPHICS AGREES TO DELAY CHALLENGED MEETING DATE
                       UNTIL AT LEAST DECEMBER 11, 1998

                 LITIGATION WILL DETERMINE ACTUAL MEETING DATE

SAN JOSE, CALIF.  NOVEMBER 20, 1998 -- Quickturn Design Systems, Inc. (Nasdaq:
QKTN) announced today that Mentor Graphics Corporation (Nasdaq: MENT) has agreed
to postpone until at least December 11, 1998 the special meeting of Quickturn
stockholders that Mentor had purported to call for November 24, 1998.

In a letter dated November 17, 1998, the Delaware Chancery Court indicated that
it might not reach a decision and issue an opinion before November 24, 1998,
regarding amendments to certain provisions of Quickturn's Bylaws and its
stockholder rights plan, which are the subject of litigation between Mentor and
Quickturn.  The Court previously noted that the issues raised in the litigation
are important to the development of Delaware corporate law.

On November 18, 1998 Quickturn renewed its previous motion for preliminary
injunction to enjoin Mentor's proposed special meeting date.   In order to give
the Court additional time to consider the issues raised in the litigation, on
November 20, 1998, Quickturn and Mentor entered into a stipulation  to be
entered as an order of the court -- in which Mentor agreed to postpone the
challenged meeting date from November 24 until at least December 11, 1998.

The Quickturn Board of Directors continues to challenge the validity and
legality of Mentor's attempt to call the special meeting as well as its ability
to set the meeting date and record date of the special meeting.  Subject to the
resolution of this litigation, the Quickturn Board has set Friday, January 8,
1999 as the date for the special stockholder meeting, in accordance with the
company's Bylaws.

Keith R. Lobo, president and chief executive officer of Quickturn Design
Systems, Inc., said, "Quickturn appreciates the Court's careful consideration of
these important corporate governance issues.  We continue to believe the
amendments to our Bylaws and stockholder rights plan are reasonable and designed
to protect the interests of Quickturn's stockholders."

Quickturn Design Systems, Inc. is the leading provider of verification products
and time-to-market engineering (TtME(TM)) services for the design of complex ICs
and electronic systems. The company's products are used worldwide by developers
of high-performance computing, multimedia, graphics and communications systems.
Quickturn is headquartered at 55 W. Trimble Road, San Jose, CA 95131-1013;
Telephone: 408/914-6000. For more information, visit the Quickturn Web site at
www.quickturn.com or send e-mail to info@quickturn.com.

                                     # # #