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SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 10-K/A

(Amendment No. 1)

(Mark
one)



|x | ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
|- | ------------------------------------------------------------------------------------

For the Fiscal Year Ended December 31, 2005

or



| ̈ | TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
|- | ----------------------------------------------------------------------------------------

For the transition period from
 to

Commission File Number 000-30231

TANOX, INC.

(Exact name of registrant as specified in its charter)



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|                                                               |  |                                     
|-------------------------------------------------------------- |  | ------------------------------------
|Delaware                                                       |  | 76-0196733                          
|(State or other jurisdiction of incorporation or organization) |  | (I.R.S. Employer Identification No.)

10301 Stella Link, Houston, Texas 77025

(Address of principal executive offices)

713-578-4000

(Registrants telephone number, including area code)



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Securities Registered Pursuant to
Section 12(b) of the Act: None

Securities Registered Pursuant to Section 12(g) of the Act: Common Stock, $.01 par value

Preferred Share Purchase Rights



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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

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the
Act.    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 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.    x

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 whether
the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).    Yes ̈No  x

The aggregate market value of the registrants common stock held
by nonaffiliates as of June 30, 2005 was $300,475,497.

Number of shares of outstanding common stock as of February 23, 2006: 44,924,706.

DOCUMENTS INCORPORATED BY REFERENCE

The information called for by Items 10, 11, 12 and 13 of Part III will be included in the registrants definitive proxy statement to be filed pursuant to Regulation 14A and is incorporated



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EXPLANATORY NOTE

Tanox, Inc. hereby files Amendment No. 1 to its Annual Report on Form 10-K for the year ended December 31, 2005. This amendment is being filed to correct a typographical error on the cover page that
incorrectly indicated that the Company is a shell company (as defined in Rule 12b-2 of the Exchange Act). The correct disclosure, which indicates that the Company is not a shell company, is contained on the cover page of this Amendment. There are no
other changes to the Annual Report on Form 10-K for the year ended December 31, 2005.



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SIGNATURE

Pursuant
to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized as of March 7, 2006.



TANOX, INC.By:

/s/ Gregory P. GuidrozGregory P. GuidrozVice President of Finance




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EXHIBIT INDEX



|     |  |                                                                                                                               
|---- |  | ------------------------------------------------------------------------------------------------------------------------------
|     | 
|31.1 |  | Certification of Chief Executive Officer pursuant to Section 13a-14(a) and Rule 15d-14(a) of the Securities Act, as amended.  
|     | 
|31.2 |  | Certification of Vice President of Finance Pursuant to Section 13a-14(a) and Rule 15d-14(a) of the Securities Act, as amended.