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Mail Stop 4561 Via fax: (408) 944-7937           A p r i l  2 1 ,  2 0 1 0   Mr. Kevin Palatnik Chief Financial Officer Cadence Design Systems, Inc 2655 Seely Avenue, Building 5 San Jose, CA 95134
Re: Cadence Design Systems, Inc.
 Form 10-K for Fiscal Year Ended December 31, 2009
Filed February 26, 2010  File No. 001-10606

Dear Mr. Palatnik:
We have reviewed your response letter  dated April 12, 2010 in connection with
the above-referenced filings and have the fo llowing comments.  If indicated, we think
you should revise your document in response to these comments.  If you disagree, we
will consider your explanation as to why our comment is inapplicable or a revision is
unnecessary.  Please be as deta iled as necessary in your expl anation.  In some of our
comments, we may ask you to provide us w ith supplemental information so we may
better understand your disclosure.  After re viewing this information, we may raise
additional comments.  Unless otherwise noted, where prior comments are referred to they
refer to our letter dated March 29, 2010.
Form 10-K for Fiscal Year Ending December 31, 2009

General
1. We note that the company’s outside lega l counsel made the Tandy representations
in your response lette rs.  Please confirm that Gibson Dunn is acting as agent for
the company in making such representati ons and provide a copy of the company’s
written authorization granting them perm ission to make such  authorizations.
Alternatively, please provide these repr esentations in a letter signed by a
representative of the company.

Mr. Kevin Palatnik
Cadence Design Systems, Inc
April 21, 2010 Page 2  Item 7.  Management’s Discussion and Analysis of Financial Condition and Results of
Operations
 Results of Operations, page 34

2. We note your response to our prior co mment 1 and your discussion regarding
specific customers for which revenues have been deferred.  Please clarify whether these are the only arrangements in fis cal 2009 for which revenues have been
deferred until payments become due and paya ble or cash is received.  If not, then
tell us the total of these arrangements for each period presented and tell us the
total revenues actually r ecognized under these arrangements for each period.
 3. We note in your response to our prior comment 2.  In an effort to better
understand the impact of the change in the business model, please tell us the
dollar amount and percentage of the tota l orders executed during fiscal 2008 for
which revenue is ratable.  In this regar d, your disclosures on page 35 indicate that
90% of your total executed orders in 2009 were comprised of ratable revenue
orders.  Please also tell us your consider ation to quantify and discuss the effect of
these events year over year.  Furthe rmore, please explain further how you
determined that the transition to a ra table business model will contribute to
increasing revenues in fiscal 2010.  In th is regard you estimate that 80% of your
fiscal 2010 revenue will come  from your backlog as of January 2, 2010.  Tell us
how this compares to fiscal 2009 where it appears that approximately 47% of your revenues came from your January 3, 2009 backlog.  Further please provide a
breakdown of your backlog at January 2, 2010 and January 3, 2009 by the various types of licenses as discussed on page 11.
4. In your response to prior comments 1 and 2 you indicate that the company will enhance your disclosures in future fili ngs. Please provide a sample of such
disclosures and clarify that  you intend to include such disclosures in your next
Form 10-Q.

* * * * * * *

Please respond to these comments within  10 business days or tell us when you
will provide us with a response.  Please  submit all correspondence and supplemental
materials on EDGAR as required by Rule 101 of Regulation S-T.  If you amend your
filing(s), you may wish to provide us with marked copies of any amendment to expedite our review.  Please furnish a cover letter that keys your response to our comments and provides any requested information.  Detailed co ver letters greatly faci litate our review.
Please understand that we may have addi tional comments after reviewing any
amendment and your response to our comments.

Mr. Kevin Palatnik
Cadence Design Systems, Inc April 21, 2010 Page 3
 You may contact Melissa Ki ndelan, Staff Accountant, at (202) 551-3564 or me at
(202) 551-3499 if you have any questions  regarding the above comments.

       S i n c e r e l y ,           Kathleen Collins
Accounting Branch Chief