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                                 UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                            ------------------------

                              AMENDMENT NO.1 TO
                                   FORM 10-K

(MARK ONE)

     [X]  ANNUAL REPORT UNDER SECTION 13 OR 15(d) OF THE
        SECURITIES EXCHANGE ACT OF 1934

                   FOR THE FISCAL YEAR ENDED JANUARY 1, 2000

     [ ]  TRANSITION REPORT UNDER SECTION 13 OR 15(d) OF THE
        SECURITIES EXCHANGE ACT OF 1934

     FOR THE TRANSITION PERIOD FROM ________________ TO ________________ .

                         COMMISSION FILE NUMBER: 1-8145

                       THORATEC LABORATORIES CORPORATION
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)

<TABLE>
<S>                                            <C>
                  CALIFORNIA                                     94-2340464
       (STATE OR OTHER JURISDICTION OF                        (I.R.S. EMPLOYER
        INCORPORATION OR ORGANIZATION)                      IDENTIFICATION NO.)

6035 STONERIDGE DRIVE, PLEASANTON, CALIFORNIA                      94588
   (ADDRESS OF PRINCIPAL EXECUTIVE OFFICES)                      (ZIP CODE)
</TABLE>

       REGISTRANT'S TELEPHONE NUMBER, INCLUDING AREA CODE: (925) 847-8600

   SECURITIES REGISTERED PURSUANT TO SECTION 12(b) OF THE EXCHANGE ACT: NONE

  SECURITIES REGISTERED PURSUANT TO SECTION 12(g) OF THE EXCHANGE ACT: COMMON
                                     STOCK

     Indicate by a check mark whether the registrant: (1) has filed all reports
required to be filed by Section 13 or 15(d) of the Securities Exchange Act of
1934 during the preceding 12 months (or for such shorter period that the
registrant was required to file such reports), and (2) has been subject to such
filing requirements for the past 90 days.  Yes [X]  No [ ]

     Indicate by a check mark if disclosure of delinquent filers pursuant to
Item 405 of Regulation S-K is not contained herein, and will not be contained,
to the best of registrant's knowledge, in definitive proxy or information
statements incorporated by reference in Part III of this Form 10-K or any
amendment to this Form 10-K.  [X]

     The aggregate market value of the voting stock held by non-affiliates was
$141,778,000 computed by reference to the last sale reported of such stock on
March 22, 2000 as listed on The Nasdaq Stock Market(R)(1)

     As of March 22, 2000, registrant had 20,629,940 shares of common stock
outstanding.

                      DOCUMENTS INCORPORATED BY REFERENCE:

     The registrant is incorporating by reference into Part III (Items 10, 11,
12 and 13) certain portions of the registrant's definitive Proxy Statement for
the 2000 Annual Meeting of Shareholders.
---------------

     (1)Exclusion of shares held by any person should not be construed to
indicate that such person possesses the power, direct or indirect, to cause the
direction of the management or policies of the issuer, or that such person is
controlled by or under common control with the issuer.

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                                   SIGNATURES

     In accordance with Section 13 or Section 15(d) of the Exchange Act, the
registrant caused this report to be signed on its behalf by the undersigned,
thereunto duly authorized.

                                          THORATEC LABORATORIES CORPORATION

                                          By:     /s/ D. KEITH GROSSMAN
                                            ------------------------------------
                                                     D. Keith Grossman
                                                  Chief Executive Officer

Date: March 30, 2000

                               POWER OF ATTORNEY

     KNOW ALL PERSONS BY THESE PRESENTS that each person whose signature appears
below constitutes and appoints D. Keith Grossman, his true and lawful
attorney-in-fact, with full power of substitution and resubstitution, to act for
him and in his name, place and stead, in any and all capacities to sign any and
all amendments to this Annual Report on Form 10-K, and to file the same, with
all exhibits thereto, and other documents in connection therewith, with the
Securities and Exchange Commission, granting unto said attorney-in-fact and
agent, full power and authority to do and perform each and every act and thing
requisite or necessary to be done in and about the premises, and fully to all
intents and purposes as he might or could do in person, hereby ratifying and
confirming all that each of attorney-in-fact and agent, or his substitute or
substitutes, may lawfully do or cause to be done by virtue hereof.

     In accordance with the Exchange Act, this report has been signed below by
the following persons on behalf of the registrant and in the capacities and on
the dates indicated.

<TABLE>
<CAPTION>
                      SIGNATURE                                     TITLE                    DATE
                      ---------                                     -----                    ----
<C>                                                    <C>                               <S>
                /s/ D. KEITH GROSSMAN                      Chief Executive Officer,      March 2, 2000
-----------------------------------------------------       President and Director
                  D. Keith Grossman

                 /s/ HOWARD E. CHASE                               Director              March 2, 2000
-----------------------------------------------------
                   Howard E. Chase

                 /s/ J. DANIEL COLE                                Director              March 2, 2000
-----------------------------------------------------
                   J. Daniel Cole

                 /s/ J. DONALD HILL                        Director and Chairman of      March 2, 2000
-----------------------------------------------------       the Board of Directors
                   J. Donald Hill

              /s/ WILLIAM M. HITCHCOCK                             Director              March 2, 2000
-----------------------------------------------------
                William M. Hitchcock

             /s/ GEORGE W. HOLBROOK, JR.                           Director              March 2, 2000
-----------------------------------------------------
               George W. Holbrook, Jr.

                /s/ DANIEL M. MULVENA                              Director              March 2, 2000
-----------------------------------------------------
                  Daniel M. Mulvena

                   /s/ CHERYL HESS                     Vice President -- Finance, Chief  March 2, 2000
-----------------------------------------------------  Financial Officer and Secretary
                     Cheryl Hess                           (Principal Financial and
                                                             Accounting Officer)
</TABLE>

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