20-F/A

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, DC 20549

FORM 20-F/A

Amendment No. 1

(Mark One)

¨ Registration statement pursuant to Section 12(b) or 12(g) of the Securities Exchange Act of 1934

or

x Annual report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

For the fiscal year ended December 31, 2008.

or

¨ Transition report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

For the transition period from              to             

or

¨ Shell company report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Date of event requiring this shell company report             

Commission file number: 001-32371

SINOVAC BIOTECH LTD.

(Exact name of Registrant as specified in its charter)

N/A

(Translation of Registrant’s name into English)

Antigua, West Indies

(Jurisdiction of incorporation or organization)

No. 39 Shangdi Xi Road,

Haidian District, Beijing 100085

People’s Republic of China

(Address of principal executive offices)

Helen G. Yang

Manager of International Business Development

No. 39 Shangdi Xi Road,

Haidian District, Beijing 100085

People’s Republic of China

Tel: +86-10-6296-3661

Fax: +86-10-6296-6910

E-mail: yangg@sinovac.com

(Name, telephone, e-mail and/or facsimile number and address of company contact person)

Securities registered or to be registered pursuant to Section 12(b) of the Act:

Title of each class	Name of each exchange on which registered
Common Shares, par value $0.001 per share	NYSE Amex

Securities registered or to be registered pursuant to Section 12(g) of the Act:

None

(Title of Class)

Securities for which there is a reporting obligation pursuant to Section 15(d) of the Act:

None

(Title of Class)

Indicate the number of outstanding shares of each of the issuer’s classes of capital or common stock as of the close of the period covered by the annual report.

42,893,928 common shares as of December 31, 2008.

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.    Yes  ¨    No  x

If this report is an annual or transition report, indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934.    Yes  ¨    No  x

Indicate by 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 check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or such shorter period that the registrant was required to submit and post such files).    Yes  ¨    No  ¨

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, or a non-accelerated filer. See definition of “accelerated filer and large accelerated filer” in Rule 12b-2 of the Exchange Act. (Check one):

Large accelerated filer  ¨    Accelerated filer  x    Non-accelerated filer  ¨    Indicate by check mark which basis of accounting the registrant has used to prepare the financial statements included in this filing:

U.S. GAAP  x    International Financial Reporting Standards as issued by the International Accounting Standards Board  ¨    Other  ¨

If “Other” has been checked in response to the previous question, indicate by check mark which financial statement item the registrant has elected to follow.    Item 17  ¨    Item 18  ¨

If this is an annual report, indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).    Yes  ¨    No  x

(APPLICABLE ONLY TO ISSUERS INVOLVED IN BANKRUPTCY PROCEEDINGS DURING THE PAST FIVE YEARS)

Indicate by check mark whether the registrant has filed all documents and reports required to be filed by Sections 12, 13 or 15(d) of the Securities Exchange Act of 1934 subsequent to the distribution of securities under a plan confirmed by a court. Yes  ¨    No  ¨

Explanatory Note

We are filing this amendment to the Sinovac Biotech Ltd. Annual Report on Form 20-F for the year ended December 31, 2008 (the “2008 20-F”), originally filed on May 1, 2009, for the purpose of filing the attestation report of our independent registered public accounting firm on our management’s conclusion regarding the effectiveness of internal control over financial reporting that was inadvertently omitted. The 2008 20-F has already disclosed that our independent registered public accounting firm has audited our internal control over financial reporting and its report on our financial statements also mentioned that it has given a separate report with an unqualified opinion on internal control over financial reporting. Solely as a result of this inadvertent omission, our Chief Executive Officer and Acting Chief Financial Officer have concluded that our disclosure controls and procedures were not effective as of December 31, 2008 (the end of our 2008 fiscal year) at the reasonable assurance level. For the convenience of the reader, this amendment sets forth (1) Part II, Item 15 in its entirety and (2) the independent registered public accounting firm’s attestation report on our internal control over financial reporting. This amendment does not change the previously reported financial statements and other financial disclosures included in the 2008 20-F. No other information in the 2008 20-F as originally filed is amended hereby, and accordingly, this amendment does not reflect events occurring after the original filing date or modify or update those disclosures affected by subsequent events. Accordingly, this Amendment No. 1 on Form 20-F should be read in conjunction with our other filings with the Securities and Exchange Commission.

ITEM 15. CONTROLS AND PROCEDURES

Disclosure Controls and Procedures

As of the end of the period covered by this annual report, our management, with the participation of our chief executive officer and acting chief financial officer, has performed an evaluation of the effectiveness of our disclosure controls and procedures within the meaning of Rules 13a-15(e) and 15d-15(e) of the Exchange Act. Based upon this evaluation, our management has concluded that, solely as a result of our inadvertent omission to include the independent registered public accounting firm’s attestation report on our internal control over financial reporting in the 2008 20-F which is corrected by the filing of this Amendment No. 1 on Form 20-F, as of the end of the period covered by this annual report, our existing disclosure controls and procedures were not effective to provide reasonable assurance that material information required to be disclosed by us in the reports that we file with, or submit to, the SEC under the Exchange Act is recorded, processed, summarized and reported within the time periods specified in by the SEC’s rules and regulations. To remediate the foregoing deficiency in our disclosure controls and procedures that led to the inadvertent omission described above, we are implementing additional steps, which include: (i) adopting additional internal review procedures with respect to required disclosures in the reports that we file with, or submit to, the SEC under the Exchange Act; (ii) enhancing our internal communication process associated with such disclosures; and (iii) improving our training and education of certain of our personnel who are involved in aspects of our reporting process.

Management’s Annual Report on Internal Control over Financial Reporting

Our management is responsible for establishing and maintaining adequate internal control over financial reporting. Our internal control system was designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation and fair presentation of its published consolidated financial statements. All internal control systems, no matter how well designed, have inherent limitations. Therefore, even those systems determined to be effective may not prevent or detect misstatements and can provide only reasonable assurance with respect to financial statement preparation and presentation. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

Our management conducted an assessment of the effectiveness of our internal control over financial reporting as of December 31, 2008. In making this assessment, it used the criteria established within the Internal Control—Integrated Framework issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO). Based on this assessment, our management has concluded that, as of December 31, 2008, our internal control over financial reporting was effective.

Our management’s assessment of the effectiveness of internal control over financial reporting as of December 31, 2008 has been audited by Ernst & Young LLP, an independent registered public accounting firm that audited the financial statements included in the annual report. The attestation report issued by Ernst & Young LLP on management’s assessment of the effectiveness of internal control over financial reporting is set forth below:

Report of Independent Registered Public Accounting Firm

on Internal Control Over Financial Reporting

To the Board of Directors and Shareholders of Sinovac Biotech Ltd.

We have audited Sinovac Biotech Ltd.’s (the “Company”) internal control over financial reporting as of December 31, 2008, based on criteria established in Internal Control—Integrated Framework issued by the Committee of Sponsoring Organizations of the Treadway Commission (the “COSO” criteria). The Company’s management is responsible for maintaining effective internal control over financial reporting and for its assessment of the effectiveness of internal control over financial reporting included in the accompanying Management’s Annual Report on Internal Control over Financial Reporting. Our responsibility is to express an opinion on the company’s internal control over financial reporting based on our audit.

We conducted our audit in accordance with the standards of the Public Company Accounting Oversight Board (United States). Those standards require that we plan and perform the audit to obtain reasonable assurance about whether effective internal control over financial reporting was maintained in all material respects. Our audit included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, testing and evaluating the design and operating effectiveness of internal control based on the assessed risk, and performing such other procedures as we considered necessary in the circumstances. We believe that our audit provides a reasonable basis for our opinion.

A company’s internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. A company’s internal control over financial reporting includes those policies and procedures that (1) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the company; (2) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles, and that receipts and expenditures of the company are being made only in accordance with authorizations of management and directors of the company; and (3) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of the company’s assets that could have a material effect on the financial statements.

Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

In our opinion, the Company maintained, in all material respects, effective internal control over financial reporting as of December 31, 2008, based on the COSO criteria.

We also have audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States), the consolidated balance sheets of the Company as of December 31, 2008 and 2007, and the related consolidated statements of operations and comprehensive income (loss), stockholders’ equity, and cash flows for each of the three years in the period ended December 31, 2008, and our report dated April 8, 2009 expressed an unqualified opinion thereon.

/s/ ERNST & YOUNG LLP

Chartered Accountants

Vancouver, Canada

April 8, 2009

Changes in Internal Control over Financial Reporting

There were no changes in our internal control over financial reporting during 2008 that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

ITEM 19. EXHIBITS

Exhibit Number	Description of Document
12.1	CEO Certification Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002
12.2	CFO Certification Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002

SIGNATURES

The registrant hereby certifies that it meets all of the requirements for filing on Form 20-F and that it has duly caused and authorized the undersigned to sign this annual report on its behalf.

SINOVAC BIOTECH LTD.
By:	/s/ Weidong Yin
Name:	Weidong Yin
Title:	Chairman and Chief Executive Officer

Date: August 20, 2009

EX-12.1

EXHIBIT 12.1

Certification by the Chief Executive Officer

Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002

I, Weidong Yin, certify that:

1. I have reviewed this annual report on Form 20-F of Sinovac Biotech Ltd. (the “Company”);

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the Company as of, and for, the periods presented in this report;

4. The Company’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the Company and have:

(a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the Company, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c) Evaluated the effectiveness of the Company’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d) Disclosed in this report any change in the Company’s internal control over financial reporting that occurred during the period covered by this annual report that has materially affected, or is reasonably likely to materially affect, the Company’s internal control over financial reporting; and

5. The Company’s other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the Company’s auditors and the audit committee of Company’s board of directors (or persons performing the equivalent function):

(a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the Company’s ability to record, process, summarize and report financial information; and

(b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the Company’s internal control over financial reporting.

Date: August 20, 2009

By:	/s/ Weidong Yin
Name:	Weidong Yin
Title:	Chief Executive Officer

EX-12.2

EXHIBIT 12.2

Certification by the Chief Financial Officer

Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002

I, Jinling Qin, certify that:

1. I have reviewed this annual report on Form 20-F of Sinovac Biotech Ltd. (the “Company”);

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the Company as of, and for, the periods presented in this report;

4. The Company’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the Company and have:

(a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the Company, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c) Evaluated the effectiveness of the Company’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d) Disclosed in this report any change in the Company’s internal control over financial reporting that occurred during the period covered by this annual report that has materially affected, or is reasonably likely to materially affect, the Company’s internal control over financial reporting; and

5. The Company’s other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the Company’s auditors and the audit committee of Company’s board of directors (or persons performing the equivalent function):

(a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the Company’s ability to record, process, summarize and report financial information; and

(b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the Company’s internal control over financial reporting.

Date: August 20, 2009

By:	/s/ Jinling Qin
Name:	Jinling Qin
Title:	Acting Chief Financial Officer