Via Facsimile and U.S. Mail
Mail Stop 6010
								January 6, 2006

Mr. Weidong Yin
President, Chief Executive Officer and Director
Sinovac Biotech Ltd.
39 Shangdi Xi Road
Haidian District
Beijing, P.R.C.  100085

Re:	Sinovac Biotech Ltd.
	Form 20-F/A for Fiscal Year Ended December 31, 2004
	Filed December 30, 2005
      File No. 1-32371

Dear Mr. Yin:

      We have reviewed the above amendment and your December 27,
2005
response letter to our December 12, 2005 comment letter and have
the
following comments.  Where indicated, we think you should revise
your
document in response to these comments.  If you disagree, we will
consider your explanation as to why our comment is inapplicable or
a
revision is unnecessary.  Please be as detailed as necessary in
your
explanation.

      Please understand that the purpose of our review process is
to
assist you in your compliance with the applicable disclosure
requirements and to enhance the overall disclosure in your filing.
We look forward to working with you in these respects.  We welcome
any questions you may have about our comments or on any other
aspect
of our review.  Feel free to call us at the telephone numbers
listed
at the end of this letter.

Form 20-F Amendment No. 4 for the year ended December 31, 2004

Item 15: Controls and Procedures, page 66

1. Your conclusion regarding your reassessment of your disclosure
controls and procedures as of December 31, 2004 in response to our
previous comment three is not clear.  Please revise your
disclosure
to specifically indicate whether the identified shortcomings in
your
disclosure controls resulted in a change of your initial
assessment.
In this regard, please specifically indicate whether your
disclosure
controls and procedures existing at December 31, 2004 were
effective
or ineffective.  If you believe your disclosure controls and
procedures were still effective, considering the identified
shortcomings and the restatements, please disclose your basis for
this conclusion.  In addition, please file currently dated
management
certifications with your amendment.

Item 17: Financial Statements, page 71

Report of Independent Registered Public Accounting Firm, page 72

2. Please have Moore Stephens Ellis Foster Ltd. revise their
report
to include an explanatory paragraph to note that the financial
statements have been restated.  Please refer to AU 420.12.

      As appropriate, please amend your Form 20-F for the year
ended
December 31, 2004 and respond to these comments within 10 business
days or tell us when you will respond.  You may wish to provide us
with marked copies of the amendment to expedite our review.
Please
furnish a cover letter with your amendment that keys your
responses
to our comments and provides any requested information.  Detailed
cover letters greatly facilitate our review.  Please file the
letter
on EDGAR under the form type label CORRESP.  Please understand
that
we may have additional comments after reviewing your amendment and
responses to our comments.

      If you have any questions, please contact Mark Brunhofer,
Staff
Accountant, at (202) 551-3638 or Donald Abbott, Senior Staff
Accountant, at (202) 551-3608.  In this regard, do not hesitate to
contact me, at (202) 551-3679.

Sincerely,



Jim B. Rosenberg
Senior Assistant Chief Accountant


cc via facsimile only:	Mr. Michael T. Shannon, Esq.
			Devlin & Jensen

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Mr. Weidong Yin
Sinovac Biotech Ltd.
January 6, 2006
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