SecProbe.io

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Via Facsimile and U.S. Mail
Mail Stop 6010
								September 12, 2005

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 September 1, 2005
      File No. 1-32371

Dear Mr. Yin:

      We have reviewed your amendment and response letter dated
August 31, 2005 to our comment letter dated August 26, 2005 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.  In some of our comments, we ask you to provide
us
with more information so we may better understand your disclosure.

      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. 1 for the year ended December 31, 2004

Item 5: Operating and Financial Review and Prospects, page 30
1. Your revised disclosures in response to previous comment two do
not appear to include an analysis of the uncertainties in applying
these accounting policies or quantification of the related
variability in operating results that you expect to be reasonably
likely to occur. Your disclosures should provide investors with a
full understanding of the uncertainties in applying critical
accounting policies and the likelihood that materially different
amounts would be reported under different conditions or using
different assumptions. For each of your critical accounting
policies,
please disclose the uncertainties in applying these critical
accounting policies, the historical accuracy of these critical
accounting estimates, a quantification of their sensitivity to
changes in key assumptions and the expected likelihood of material
changes in the future.
2. Please revise the disclosure you added in response to previous
comment four to specifically disclose the gross profit and gross
margins including depreciation and amortization excluded from cost
of
sales.   Please revise your 2003 versus 2002 operating results
discussion accordingly.

Item 11: Quantitative and Qualitative Disclosures About Market
Risk,
page 61
3. We acknowledge your revised disclosure in response to our
previous
comment three.  Instruction 3A to Item 11(a) of Form 20-F
generally
requires sensitivity analyses to include hypothetical market rate
changes of at least 10%.  Please revise your disclosure to comply
or
disclose the economic justification for selecting a 5% rate
change.
In addition, please revise your disclosure to indicate that you
believe the selected rate change is reasonably possible in the
near
term.

Item 17: Financial Statements, page 67

Consolidated Statements of Operations, page 72
4. We agree with your statement in response to our previous
comment
five that your interest and financing expenses do not meet the
definition of non-operating expenses under Rule 5-03(b)9 of
Regulation S-X.  However, interest expense under Rule 5-03(b)8 is
also a non-operating item along with non-operating income, such as
interest income, under Rule 5-03(b)7.  Please revise your
consolidated statements of operations to reclassify interest and
financing expenses as a non-operating item or remove your total
operating expenses and operating loss subtotals.

Note 1: Nature of Business, page 74
5. Please revise your disclosure to clarify how Sinovac controlled
the combined entity after the acquisition of Net-Force consistent
with your response to previous comment six.  In your revised
disclosure, please indicate that outside the Share Purchase
Agreement, a member of Sinovac management purchased 6,544,830
shares
of the 17,091,032 shares of Net-Force resulting in shareholders
and
management of Sinovac having control of the combined entity.
6. In your response to our previous comment seven you indicate
that
no shares of Sinovac Beijing were outstanding prior to the reverse
acquisition transaction.   Please explain to us why section 1.02
of
the Share Purchase Agreement filed as Exhibit 10.1 to the Form 6-
K/A
filed by Net-Force on October 29, 2003 indicates that 133,600,000
shares of common stock of Sinovac Beijing were issued and
outstanding
on August 31, 2003.  If stock of Sinovac Beijing was indeed issued
and outstanding prior to the reverse acquisition, please revise
your
financial statements to reflect all shares of Sinovac Beijing when
actually issued adjusted for the 6.8136-to-one effective exchange
ratio inherent in the Share Purchase Agreement.  Please ensure
that
you reflect a share reduction for the effective spin-off
representing
the 49% minority interest created in the reverse acquisition
transaction as well as the new shares effectively issued to the
shareholders of Net-Force.  If you do not agree with this
accounting,
please tell us why and reference the authoritative literature you
relied upon to support your position.
7. We note that your weighted-average share computations for 2002
and
2003 provided in response to our previous comment seven do not
include the shares outstanding that were held by shareholders that
now comprise the minority interest.  Consistent with the
immediately
preceding comment, please provide us with revised 2002 and 2003
weighted-average share computations that reflect all Sinovac
Beijing
shares issued and outstanding along with a share reduction for the
effective spin-off representing the 49% minority interest.  In
addition, please revise your financial statement disclosure to
reflect the revised loss per share information.

Note 7: Licenses and Permits, page 84
8. Please revise your disclosure to indicate the nature of the
costs
associated with your inactive hepatitis A licenses, consistent
with
your response to our previous comment eight.
9. As previously requested in our previous comment nine, please
tell
us the authoritative guidance you relied upon to defer
amortization
of your recombinant hepatitis A&B vaccine and your influenza virus
HA
vaccine licenses until you start drug production.  We believe that
paragraph 12 of SFAS 142 would require that if a pattern of
economic
benefits cannot be reliably determined, straight-line amortization
method should be used commencing upon acquisition of the
intangible
asset.

Note 9:  Income Taxes, page 86
10. We acknowledge your response to our previous comment 10.
Please
tell us whether you file separate or consolidated Chinese income
tax
returns for Sinovac China and Tangshan Yian.  In addition, please
tell us how one year of profitable operations at Sinovac China
provides evidence of a strong earnings history as contemplated in
paragraph 24 of SFAS 109.  We note that paragraph 23 of SFAS 109
specifically indicates that it is difficult to conclude that a
valuation allowance is not needed in the presence of a history of
losses.

      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:	Mr. Michael T. Shannon, Esq.
	Devlin & Jensen

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Mr. Weidong Yin
Sinovac Biotech Ltd.
September 12, 2005
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