PROSPECTUS SUPPLEMENT NO. 1
(To Prospectus dated November 24, 2000)

                         [INTERNATIONAL RECTIFIER LOGO]
                      INTERNATIONAL RECTIFIER CORPORATION

          $550,000,000 4 1/4% CONVERTIBLE SUBORDINATED NOTES DUE 2007
                                      AND
     7,438,967 SHARES OF COMMON STOCK ISSUABLE UPON CONVERSION OF THE NOTES

    This prospectus supplement relates to the resale by holders of our 4 1/4%
Convertible Subordinated Notes Due 2007 and shares of common stock issuable upon
the conversion of the notes. This prospectus supplement may only be delivered or
used in connection with our prospectus dated November 24, 2000. Our common stock
is listed on The New York Stock Exchange and the Pacific Exchange under the
symbol "IRF."

    NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES
COMMISSION HAS APPROVED OR DISAPPROVED OF THESE SECURITIES OR PASSED UPON THE
ADEQUACY OR ACCURACY OF THIS PROSPECTUS SUPPLEMENT OR THE RELATED PROSPECTUS.
ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.

                  PROSPECTUS SUPPLEMENT DATED DECEMBER 1, 2000

    The information appearing in the following table supplements or supersedes
in part the information in the table under the heading "Selling Holders" in our
prospectus and was provided by or on behalf of the selling holders.



                                                                                                               COMMON
                                                                                                                STOCK
                                                                                                            BENEFICIALLY
                                                                                                             OWNED AFTER
                                             PRINCIPAL AMOUNT OF      COMMON STOCK                            OFFERING
                                             NOTES BENEFICIALLY    BENEFICIALLY OWNED    COMMON STOCK    -------------------
             NAME AND ADDRESS                 OWNED AND OFFERED     BEFORE OFFERING      OFFERED (1)      AMOUNT       %
- -------------------------------------------  -------------------   ------------------   --------------   --------   --------
                                                                                                     
Bankers Trust Company Trustee
  For Daimler Chrysler Corp
  Emp #1 Pension Plan......................     $  3,655,000               0                 49,435         0          *
  c/o Palisade Capital Mgt, L.L.C.
  1 Bridge Plaza, Suite 695
  Fort Lee, NJ 07024
BBT Fund, L.P..............................     $ 17,500,000               0                236,694         0          *
  201 Main St., Suite 3200
  Fort Worth, TX 76102
CIBC World Markets.........................     $ 10,695,000               0                144,654         0          *
  1 World Financial Center
  200 Liberty St., 8th Floor
  New York, NY 10281
Deutsche Bank Securities...................     $ 29,757,000               0                402,475         0          *
  1251 Avenue of Americas
  26th Floor
  New York, NY 10020
Forest Alternative Strategies
  Fund II LP ASM...........................     $     65,000               0                    879         0          *
  53 Forest Avenue
  Old Greenwich, CT 06870
Franklin and Marshall College..............     $    245,000               0                  3,314         0          *
  c/o Palisade Capital Mgt., L.L.C.
  1 Bridge Plaza, Suite 695
  Fort Lee, NJ 07024
Morgan Stanley & Co........................     $ 12,899,000               0                174,464         0          *
  1585 Broadway
  New York, NY 10036
Penn Treaty Network America
  Insurance Company........................     $    295,000               0                  3,990         0          *
  c/o Palisade Capital Mgt., L.L.C.
  1 Bridge Plaza, Suite 695
  Fort Lee, NJ 07024
Pilgrim Convertible Fund...................     $  3,459,000               0                 46,784         0          *
  7337 E. Doubletree Ranch Rd.
  Scottsdale, AZ 85258
State Street Bank Custodian For
  GE Pension Trust.........................     $  1,805,000               0                 24,413         0          *
  c/o Palisade Capital Mgt., L.L.C.
  1 Bridge Plaza, Suite 695
  Fort Lee, NJ 07024
Zurich HFR Master Hedge Fund
  Index Ltd................................     $    120,000               0                  1,623         0          *
  c/o Noddings Investments
  700 Market Street
  St. Louis, MO 63101
Any other holder of notes or
  future transferee, pledgee, donee
  or successor of any holder (2)(3)........     $117,796,000               0              1,593,238         0          *


- ------------------------------
*   Less than 1%.

(1) Assumes conversion of all the holder's notes at a conversion price of
    $73.935 per share of common stock and resale of all shares of common stock
    offered hereby.

(2) Information about other selling security holders will be set forth in
    prospectus supplements, if required.

(3) Assumes that any other holders of notes, or any future transferees,
    pledgees, donees or successors of or from any such other holders of notes,
    do not beneficially own any common stock other than the common stock
    issuable upon conversion of the notes at the initial conversion rate.

                                      S-2

    Information concerning the selling holders may change from time to time and
any changed information will be set forth in supplements or amendments to the
prospectus if necessary. In addition, the per share conversion price, and
therefore the number of shares of common stock issuable upon conversion of the
notes, is subject to adjustment. As a result, the aggregate principal amount of
the notes and the number of shares of common stock into which the notes are
convertible may increase or decrease.

                                      S-3