As filed with the Securities and Exchange Commission on December 29, 2003.

REGISTRATION NO. 333-3433
================================================================================

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
POST-EFFECTIVE AMENDMENT NO. 1 TO
FORM S-3
REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933

ENCYSIVE PHARMACEUTICALS INC.
(Exact name of registrant as specified in its charter)

DELAWARE 13-3532643
(State or other jurisdiction (I.R.S. Employer
of incorporation or organization) Identification Number)

6700 WEST LOOP SOUTH, 4TH FLOOR
BELLAIRE, TEXAS 77401
(713) 796-8822
(Address, including zip code, and telephone number, including area code, of
registrant's principal executive offices)

BRUCE D. GIVEN, M.D. With copies to:
ENCYSIVE PHARMACEUTICALS INC. PORTER & HEDGES, L.L.P.
6700 WEST LOOP SOUTH, 4TH FLOOR 700 LOUISIANA, 35TH FLOOR
BELLAIRE, TEXAS 77401 HOUSTON, TEXAS 77002-2764
(713) 796-8822 ATTN: ROBERT G. REEDY
(Name and address, including zip code, and TELEPHONE (713) 226-0647
telephone number, including area code, TELECOPY (713) 226-0247
of agent for service)

Approximate date of commencement of proposed sale to the public: Not
applicable. Deregistration of unsold securities.

If the only securities being registered on this Form are being offered
pursuant to dividend or interest reinvestment plans, please check the following
box. [ ]

If any of the securities being registered on this Form are to be
offered on a delayed or continuous basis pursuant to Rule 415 under the
Securities Act of 1933, other than securities offered only in connection with a
dividend or interest reinvestment plan, please check the following box. [ ]

If this Form is filed to register additional securities for an offering
pursuant to Rule 462(b) under the Securities Act of 1933, please check the
following box and list the Securities Act of 1933 registration statement number
of the earlier effective registration statement for the same offering. [ ]
______________

If this Form is a post-effective amendment filed pursuant to Rule
462(c) under the Securities Act of 1933, check the following box and list the
Securities Act of 1933 registration statement number of the earlier effective
registration statement for the same offering. [ ] ______________

If delivery of the prospectus is expected to be made pursuant to Rule
434, please check the following box. [ ]

DEREGISTRATION OF SECURITIES

On May 10, 1996, Encysive Pharmaceuticals Inc (formerly Texas
Biotechnology Corporation) (the "Company") filed a registration statement on
Form S-3 (No. 333-3433) and on May 30, 1996, the Company filed an amendment
thereto (as amended, the "Registration Statement"). The Registration Statement
registered for resale by the selling shareholders named therein a total of
7,273,928 shares of the Company's common stock, par value $.005 per share (the
"Common Stock"). The Company's contractual obligations to the selling
shareholders to maintain the effectiveness of the Registration Statement has
expired. Pursuant to the undertaking contained in the Registration Statement,
the Company files this post-effective Amendment to the Registration Statement to
terminate the Registration Statement and deregister all of the shares of Common
Stock registered for resale thereunder that remain unsold as of the date hereof.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the
registrant certifies that it has reasonable grounds to believe that it meets all
of the requirements for filing on Form S-3 and has duly caused this
post-effective amendment to the Registration Statement to be signed on its
behalf by the undersigned, thereunto duly authorized, in the City of Bellaire,
State of Texas on December 29, 2003.

ENCYSIVE PHARMACEUTICALS INC.

By: /s/ BRUCE D. GIVEN, M.D.
-------------------------
Bruce D. Given, M.D.
President and Chief
Executive Officer

POWER OF ATTORNEY

Each of the undersigned hereby appoints Bruce D. Given and Stephen L.
Mueller and each of them (with full power to act alone), as attorney and agents
for the undersigned, with full power of substitution, for and in the name, place
and stead of the undersigned, to sign and file with the Securities and Exchange
Commission under the Securities Act of 1933 any and all amendments and exhibits
to this registration statement and any and all applications, instruments and
other documents to be filed with the Securities and Exchange Commission
pertaining to the registration of the securities covered hereby, with full power
and authority to do and perform any and all acts and things whatsoever requisite
or desirable.

Pursuant to the requirements of the Securities Act of 1933, this
registration statement has been signed below by the following persons in the
capacities and on the 29th day of December, 2003.

SIGNATURE TITLE
--------- -----

*
--------------------------------------------------------- Chairman of the Board of Directors
John M. Pietruski

/s/ BRUCE D. GIVEN, M.D.
--------------------------------------------------------- Director, President and Chief Executive Officer
Bruce D. Given, M.D. (Principal Executive Officer)

*
--------------------------------------------------------- Director, Senior Vice President, Research and Chief
Richard A.F. Dixon, Ph.D. Scientific Officer

*
--------------------------------------------------------- Vice President, Finance and Administration,
Stephen L. Mueller Treasurer and Secretary
(Principal Financial and Accounting Officer)

--------------------------------------------------------- Director
Ron J. Anderson, M.D.

SIGNATURE TITLE
--------- -----

Director
*
---------------------------------------------------------
Frank C. Carlucci

* Director
---------------------------------------------------------
Robert J. Cruikshank

Director
---------------------------------------------------------
Suzanne Oparil, M.D.

Director
---------------------------------------------------------
William R. Ringo, Jr.

* Director
---------------------------------------------------------
James A. Thomson, Ph.D.

* Director
---------------------------------------------------------
James T. Willerson, M.D.

*By: /s/ STEPHEN L. MUELLER
-----------------------------------------------------
Stephen L. Mueller
individually and as attorney-in-fact