SCHEDULE 14A
                                (RULE 14a-101)
                    INFORMATION REQUIRED IN PROXY STATEMENT
                           SCHEDULE 14A INFORMATION

               PROXY STATEMENT PURSUANT TO SECTION 14(a) OF THE
                        SECURITIES EXCHANGE ACT OF 1934

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 Rule 14a-6(e)(2))

    [ ] Definitive proxy statement

    [ ] Definitive additional materials

    [X] Soliciting material pursuant to (S) 240.14a-11(c) or (S) 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):

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    [ ] Fee computed on table below per Exchange Act Rules 14a-6(i)(1) and 0-11.


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            _______________________________________


        (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):

            _______________________________


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            ____________________________________


        (5) Total fee paid:  ____________________________________

    [ ] Fee paid previously with preliminary materials.

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previously. Identify the previous filing by registration statement number, or
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        (1)  Amount Previously Paid:  ________________________________

        (2)  Form, Schedule or Registration Statement No.:   ___________________
        
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        (4)  Date Filed:  _________________________________



 
                                                             September 14, 1998
 
Dear Fellow Stockholder:
 
  I am writing to you about an urgent matter concerning the future of your
investment in Quickturn Design Systems, Inc. You may have received, or will
likely soon receive, a communication from Mentor Graphics Corporation that
attempts to call a special stockholder meeting and attempts to solicit your
vote to replace Quickturn's Board of Directors with Mentor's hand-picked
nominees, all in an effort to implement Mentor's inadequate $12.125 per share
tender offer.
 
                      THERE IS ABSOLUTELY NO NEED FOR YOU
                        TO TAKE ANY ACTION AT THIS TIME
 
  Do not be confused by Mentor's purported call of a special stockholder
meeting. The validity and legality of Mentor's attempt to call such a meeting
is currently the subject of litigation between Mentor and Quickturn. No
meeting date will be finally determined until this litigation is resolved.
Your Board urges you to take no action with respect to Mentor's gold proxy
cards until and unless it is determined that Mentor has validly called a
special meeting.
 
  Your Board of Directors will soon send to you its own solicitation
materials. We strongly recommend that you take no action until you have
received these materials. These materials will also provide you with the
opportunity to reconsider any decision you may have made to send a proxy card
to Mentor. After careful consideration of the Mentor offer, your Board of
Directors has determined that the Mentor offer is inadequate and not in the
best interests of the Company's stockholders, that the Mentor offer does not
fully reflect the long-term value of the Company, and that stockholder
interests would be better served by the Company continuing to pursue its
business plan.
 
  Your Board of Directors believes that Mentor's rush to seek your vote in
favor of their proposals is nothing more than a pressure tactic to carry out
its opportunistic hostile takeover of Quickturn. Mentor has stated that its
purpose in soliciting your vote in favor of its proposals is to facilitate the
Mentor offer, which your Board has determined to be inadequate.
 
            DO NOT BE STAMPEDED BY MENTOR'S ATTEMPT TO SOLICIT YOUR
               VOTE BEFORE YOU HEAR FROM YOUR BOARD OF DIRECTORS
 
  Again, we urge stockholders not to take any action until you have received
our materials, and not to execute any gold Mentor proxy card at this time. If
you have any questions about this process or need further assistance, please
contact our proxy solicitor:
 
                               MORROW & CO., AT
                         1 (800) 566-9061 (TOLL-FREE)
 
  We have every confidence in our Company's future and wish to reaffirm our
determination that you, our stockholders, be given every opportunity to
participate fully in that future. Your Board of Directors and I greatly
appreciate your continued support and encouragement.
 
                                          Very truly yours
 
 
                                          /s/ KEITH R. LOBO
                                          Keith R. Lobo
                                          PRESIDENT AND CHIEF EXECUTIVE
                                           OFFICER

 
                  CERTAIN INFORMATION CONCERNING PARTICIPANTS
 
  The following is a list of the names and stock holdings of individuals who
may be deemed to be "participants" in the solicitation of proxies or
revocation of agent designations by Quickturn Design Systems, Inc. in
opposition to Mentor Graphics's solicitation of agent designations to call a
special meeting of stockholders (information with respect to stockholdings
includes common stock and stock issuable pursuant to options exercisable
within 60 days): Richard C. Alberding (17,500); Glen M. Antle (325,782);
Michael R. D'Amour (40,971); William A. Hasler (3,667); Dr. Yen-Son (Paul)
Huang (354,550), Charles D. Kissner (1,667); Dr. David K. Lam (10,417); Keith
R. Lobo (438,750); Michael Ferguson (none); Jeffrey K. Jordan (1,134), Donald
J. McInnis (369,051); Raymond K. Ostby (102,767); Dugald H. Stewart (7,390);
Christopher J. Tice (22,802); Tung-sun Tung (34,665); Naeem Zafar (34,713). In
addition, Quickturn and its Board of Directors are currently the subject of
class action litigation in which the plaintiffs are alleging that the Company
and the Board have breached their fiduciary duties to the Company's
stockholders by failing to maximize stockholder value, patent litigation
initiated jointly by Aptix Corporation and Meta, a French subsidiary of
Mentor, patent litigation filed by Mentor and its subsidiaries, a complaint
filed by Mentor in Delaware state court seeking a ruling enjoining the Company
and the Board from preventing the tender offer initiated by Mentor and MGZ
from succeeding, and a complaint filed by Mentor against the Company in
Delaware federal court seeking a declaratory judgment that Mentor and MGZ are
in full compliance with federal securities laws, to which the Company has
filed counterclaims seeking injunctive relief and alleging violation of the
federal securities laws.