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                                  EXHIBIT 32.1
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           This is an Exhibit to the Form 20-F of Sinovac Biotech Ltd.
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                     Attached find the following materials:


              Certification of Weidong Yin pursuant to Section 906
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                        of the Sarbanes-Oxley Act of 2002
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                            CERTIFICATION PURSUANT TO
                             18 U.S.C. SECTION 1350,
                             AS ADOPTED PURSUANT TO
                  SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002


In connection  with  the Annual  Report  on Form 20-F/A-3 for fiscal  year ended
December 31, 2004  of Sinovac Biotech Ltd.,  a company  organized under the laws
of  Antigua  and  Barbuda (the "Company"),  as filed  with  the  Securities  and
Exchange  Commission  on the date hereof (the "Annual Report"), I,  Weidong Yin,
President  and Chief  Executive  Officer of the  Company certify, pursuant to 18
U.S.C. Section 1350  as  adopted  pursuant  to Section 906 of the Sarbanes-Oxley
Act of 2002, that:


1.   The Annual Report fully complies with the  requirements of Section 13(a) or
     15(d) of the Securities Exchange Act of 1934, as amended; and

2.   The  information  contained in the Annual  Report fairly  presents,  in all
     material respects, the financial condition and results of operations of the
     Company.



Dated: November 21, 2005                       /s/ Weidong Yin
                                            ------------------------------------
                                            Weidong Yin, President, CEO and
                                            Director















                               End of Exhibit 32.1

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