UNITED STATES
                             SECURITIES AND EXCHANGE COMMISSION
                                   Washington, D.C. 20549


                                        SCHEDULE 13G
                         Under the Securities Exchange Act of 1934
                                     (Amendment No. 6)*

                              Cadence Design Systems, Inc.

                                    (Name of Issuer)

                                      Common Stock

                             (Title of Class of Securities)

                                       127387108

                                     (CUSIP Number)
                                       12/30/2005

                (Date of Event Which Requires Filing of this Statement)



Check the appropriate box to designate the rule pursuant to which this Schedule is filed:
[X]      Rule 13d-1(b)
[  ]     Rule 13d-1(c)
[  ]     Rule 13d-1(d)

*The remainder of this cover page shall be filled out for a reporting person's initial
filing on this form with respect to the subject class of securities, and for any subsequent
amendment containing information which would alter the disclosures provided in a prior
cover page.

The information required in the remainder of this cover page shall not be deemed to be
"filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or
otherwise subject to the liabilities of that section of the Act but shall be subject to all
other provisions of the Act (however, see the Notes).














 ------------------------------------------------------------------------------------------

  CUSIP No. 127387108

 ------------------------------------------------------------------------------------------
 ------------------------------------------------------------------------------------------

       1.       Names of Reporting Persons
                IRS Identification No:

                OppenheimerFunds, Inc.
                13-2527171
 ------------------------------------------------------------------------------------------
 ------------------------------------------------------------------------------------------

       2.        Check the Appropriate Box if a Member of a Group (See Instructions):
                 Joint filing


 ------------------------------------------------------------------------------------------
 ------------------------------------------------------------------------------------------

       3.       SEC Use Only
 ------------------------------------------------------------------------------------------
 ------------------------------------------------------------------------------------------

       4.       Citizenship or Place of Organization:
                Colorado
 ------------------------------------------------------------------------------------------
 ------------------------------------------------------------------------------------------
   Number of
     Shares     5.    Sole Voting Power:
  Beneficially       0
    Owned by
      Each
   Reporting
  Person With
 ------------------------------------------------------------------------------------------
 ------------------------------------------------------------------------------------------

                6.    Shared Voting Power:
                     11,412,015
 ------------------------------------------------------------------------------------------
 ------------------------------------------------------------------------------------------

                7.    Sole Dispositive Power:
                     0
 ------------------------------------------------------------------------------------------
 ------------------------------------------------------------------------------------------

                8.    Shared Dispositive Power:
                     11,412,015
 ------------------------------------------------------------------------------------------
 ------------------------------------------------------------------------------------------

       9.       Aggregate Amount Beneficially Owned by Each Reporting Person:
                11,412,015 (beneficial ownership disclaimed pursuant to Rule 13d-4 of the
                Exchange Act of 1934)
 ------------------------------------------------------------------------------------------
 ------------------------------------------------------------------------------------------

      10.       Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See
                Instructions)
                [  ]
 ------------------------------------------------------------------------------------------
 ------------------------------------------------------------------------------------------

      11.       Percent of Class Represented by Amount in Row (11):
                4.02%
 ------------------------------------------------------------------------------------------
 ------------------------------------------------------------------------------------------

      12.       Type of Reporting Person (See Instructions):
                IA
 ------------------------------------------------------------------------------------------







 ---------------------------------------------------------------------------------------
 Item:
 ---------------------------------------------------------------------------------------






 ---------------------------------------------------------------------------------------

      1(a)      Name of Issuer:
                Cadence Design Systems, Inc.
 ---------------------------------------------------------------------------------------
 ---------------------------------------------------------------------------------------

      1(b)      Address of Issuer's Principal Executive Offices:
                2655 Seely Avenue, Bldg. 5, Mail Stop 5B2
                San Jose, CA   95134
 ---------------------------------------------------------------------------------------
 ---------------------------------------------------------------------------------------

      2(a)      Name of Person Filing:
                OppenheimerFunds, Inc.
 ---------------------------------------------------------------------------------------
 ---------------------------------------------------------------------------------------

      2(b)      Address of Principal Business Office or, if none, Residence:
                Two World Financial Center
                225 Liberty Street, 11th Floor
                New York, NY 10281-1008
 ---------------------------------------------------------------------------------------
 ---------------------------------------------------------------------------------------

      2(c)      Citizenship:
                Colorado
 ---------------------------------------------------------------------------------------
 ---------------------------------------------------------------------------------------

      2(d)      Title of Class of Securities:
                Common Stock
 ---------------------------------------------------------------------------------------
 ---------------------------------------------------------------------------------------

      2(e)      CUSIP Number:
                127387108
 ---------------------------------------------------------------------------------------
 ---------------------------------------------------------------------------------------

       3        OppenheimerFunds, Inc. is an investment adviser in accordance with
                Rule 13d-1(b)(1)(ii)(E).

 ---------------------------------------------------------------------------------------
 ---------------------------------------------------------------------------------------

      4(a)      Amount beneficially owned:
                11,412,015 (beneficial ownership disclaimed pursuant to Rule 13d-4 of
                the Exchange Act of 1934)
 ---------------------------------------------------------------------------------------
 ---------------------------------------------------------------------------------------

      4(b)      Percent of class:
                4.02%
 ---------------------------------------------------------------------------------------
 ---------------------------------------------------------------------------------------

      4(c)      Number of shares as to which the person has:

          (i)   Sole power to vote or to direct the vote:
                0
          (ii)  Shared power to vote or to direct the vote:
                11,412,015
          (iii) Sole power to dispose or to direct the disposition of:
                0
          (iv)  Shared power to dispose or to direct the disposition of:
                11,412,015
 ---------------------------------------------------------------------------------------
 ---------------------------------------------------------------------------------------

       5.       Ownership of Five Percent or Less of a Class: [ X]
 ---------------------------------------------------------------------------------------
 ---------------------------------------------------------------------------------------

       6.       Ownership of More than Five Percent on Behalf of Another Person.: N/A

 ---------------------------------------------------------------------------------------
 ---------------------------------------------------------------------------------------

       7.       Identification and Classification of the Subsidiary Which Acquired the
                Security Being Reported on By the Parent Holding Company:
                N/A
 ---------------------------------------------------------------------------------------
 ---------------------------------------------------------------------------------------

       8.       Identification and Classification of Members of the Group:
                N/A
 ---------------------------------------------------------------------------------------
 ---------------------------------------------------------------------------------------

       9.       Notice of Dissolution of Group:
                N/A
 ---------------------------------------------------------------------------------------
 ---------------------------------------------------------------------------------------

      10.       Certification:
                By signing below I certify that, to the best of my knowledge and
                belief, the securities referred to above were acquired and are held in
                the ordinary course of business and were not acquired and are not held
                for the purpose of or with the effect of changing or influencing the
                control of the issuer of the securities and were not acquired and are
                not held in connection with or as a participant in any transaction
                having that purpose or effect.
 ---------------------------------------------------------------------------------------

                                         SIGNATURE
After reasonable inquiry and to the best of my knowledge and belief, I certify that the
information set forth in this statement is true, complete and correct.


                                                            02/08/2006
                                                            Date

                                                      /s/ Mark Vandehey
                                                            Signature

                                                   Mark Vandehey, Senior Vice President
                                                        and Chief Compliance Officer
                                                            Name/Title

















Cadence Design Systems a6 13g(123005).rtf