UNITED STATES SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

Commission file number 1-4448

Baxter International Inc.

(Exact Name of Registrant as Specified in its Charter)

Registrant’s telephone number, including area code  847.948.2000

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

Securities registered pursuant to Section 12(g) of the Act: None

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

     Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or 15(d) of the Act.  Yes o  No þ

     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 þ  No o

     Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein and will not be contained, to the best of registrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K.  þ

     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.

     Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act).  Yes o  No þ

     The aggregate market value of the voting common equity held by non-affiliates of the registrant as of June 30, 2005 (the last business day of the registrant’s most recently completed second fiscal quarter), based on the per share closing sale price of $37.10 on that date and the assumption for the purpose of this computation only that all of the registrant’s directors and executive officers are affiliates, was approximately $24.0 billion. There is no non-voting common equity held by non-affiliates of the registrant.

     The number of shares of the registrant’s common stock, $1.00 par value, outstanding as of January 31, 2006 was 648,483,996.

DOCUMENTS INCORPORATED BY REFERENCE

     Portions of the registrant’s Annual Report to Shareholders for fiscal year ended December 31, 2005 are incorporated by reference into Parts I, II and IV of this report. Portions of the registrant’s definitive 2006 proxy statement for use in connection with its Annual Meeting of Shareholders to be held on May 9, 2006 are incorporated by reference into Part III of this report.

TABLE OF CONTENTS