Securities and Exchange Commission
                             Washington, D. C. 20549

                                  Schedule 13G
                    Under the Securities Exchange Act of 1934

                              CV Therapeutics, Inc.
                                  Common Stock
                             CUSIP Number 126667104



Date of Event Which Requires Filing of this Statement:     December 31, 2005

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)

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CUSIP No. 126667104

         1)   Name of reporting person:
                  Legg Mason Capital Management, Inc.
               Tax Identification No.:
                   52-1268629

         2)   Check the appropriate box if a member of a group:
                  a)     x
                  b)     n/a

         3)    SEC use only

         4)     Place of organization:
                  Maryland

Number of shares beneficially owned by each reporting person with:
         5)     Sole voting power:          - 0 -
         6)     Shared voting power:        2,991,725
         7)     Sole dispositive power:     - 0 -
         8)     Shared dispositive power:   2,991,725

         9)     Aggregate amount beneficially owned by each reporting person:
                  2,991,725

         10)   Check if the aggregate amount in row (9) excludes certain shares:
                  n/a

         11)    Percent of class represented by amount in row (9):
                  6.69%

         12)    Type of reporting person:
                  IA, CO

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         Item 1a)     Name of issuer:
                           CV Therapeutics, Inc.

         Item 1b)     Address of issuer's principal executive offices:
                           3172 PORTER DRIVE
                           PALO ALTO CA 94304

         Item 2a)    Name of person filing:
                           Legg Mason Capital Management, Inc.

         Item 2b)    Address of  principal business office:
                           100 Light Street
                           Baltimore, MD  21202

         Item 2c)    Citizenship:
                           Legg Mason Capital Management, Inc.
                                    Maryland corporation

         Item 2d)    Title of class of securities:
                           Common Stock

         Item 2e)    CUSIP number:     126667104

         Item 3)  If this statement is filed pursuant to Rule 13d-1(b), or
                  13d-2(b), check whether the person filing is a :
         (a)[   ] Broker or dealer under Section 15 of the Act.
         (b)[   ] Bank as defined in Section 3(a)(6) of the Act.
         (c)[   ] Insurance Company as defined in Section 3(a)(6) of the Act.
         (d)[   ] Investment Company registered under Section 8 of the
                  Investment Company Act.
         (e)[  X] Investment Adviser registered under Section 203 of the
                  Investment Advisers Act of 1940.
         (f)[   ] Employee Benefit Plan, Pension Fund which is subject to ERISA
                  of 1974 or Endowment Funds; see 240.13d-1(b)(ii)(F).
         (g)[   ] Parent holding company, in accordance with 240.13d-1(b)(ii)(G)
         (h)[   ] Group, in accordance with 240.13d-1(b)(1)(ii)(J).

         Item 4)    Ownership:

         (a)     Amount beneficially owned:             2,991,725

         (b)     Percent of Class:  6.69%

         (c)     Number of shares as to which such person has:
                  (i)    sole power to vote or to direct the vote:
                                    -  0 -
                  (ii)   shared power to vote or to direct the vote:
                                    2,991,725
                  (iii)  sole power to dispose or to direct the disposition of:
                                    - 0 -
                  (iv)  shared power to dispose or to direct the disposition of:
                                   2,991,725

         Item 5)    Ownership of Five Percent or less of a class:
                           n/a

         Item 6)    Ownership of more than Five Percent on behalf of another
                    person:

                  Various accounts managed by Legg Mason Capital Managment, Inc.
                  have the right to receive or the power to direct the receipt
                  of dividends from, or the proceeds from the sale of shares of
                  the issuer. No such account owns more than 5% of the shares
                  outstanding.


         Item 7)    Identification and classification of the subsidiary which
                    acquired the security being reported on by the parent
                    holding company:
                           n/a

         Item 8)    Identification and classification of members of the group:
                         n/a

         Item 9)    Notice of dissolution of group:
                           n/a

         Item 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.

         --------------------------------
         Date - February 14, 2006


         Legg Mason Capital Management, Inc.


         By___________________________________________
                Andrew J. Bowden, Senior Vice President