EXHIBIT 10.4

                              SECOND AMENDMENT TO
                     AMENDED AND RESTATED LICENSE AGREEMENT



         This  Second  Amendment  to  Amended  and  Restated  License  Agreement
("Second  Amendment")  effective this _______ day of April,  2006 is between the
University of Chicago, an Illinois  not-for-profit  corporation  ("UNIVERSITY"),
having its principal  office at 5555 S. Woodlawn Avenue,  Chicago,  IL 60637 and
PharmaFrontiers  Corp.,  a Texas  corporation  ("PHARMA")  having its  principal
office at 2635 N.  Crescent  Ridge  Drive,  The  Woodlands,  Texas  77381.  Each
hereunder  may be referred to separately  as the  ("Party"),  or together as the
("Parties"). The Parties agree:

                                                     RECITALS

A.            UNIVERSITY and PHARMA have  previously  entered in an "Amended and
              Restated License  Agreement" dated December 30, 2004 (the "License
              Agreement"); and

B.            UNIVERSITY  and  PHARMA  have  previously   entered  in  a  "First
              Amendment to Amended and Restated License Agreement" dated October
              31, 2005 (the First Amendment); and

C.            NOW,  THEREFORE,  in  consideration  of the  mutual  promises  and
              obligations  hereinafter set forth and for other good and valuable
              consideration,  the  receipt and  sufficiency  of which are hereby
              acknowledged, the Parties hereto agree as follows:

                  1.0      AMENDMENT   OF   PARAGRAPH   4.C.I  OF  THE   LICENSE
                           AGREEMENT,  AS AMENDED IN SECTION B. 1.0 OF THE FIRST
                           AMENDMENT:  The first  sentence  of  Paragraph  4.C.i
                           shall be deleted and replaced with

                               "PF shall pay to the  University one and one half
                               million ($1,500,000) US dollars upon the later of
                               the occurrence of the First  Financing or October
                               31, 2006."

                      Also,  in each instance in which the date "April 30, 2006"
                      appears in  Paragraph  4.C.i.  such date shall be replaced
                      with "October 31, 2006".

                  2.0      AMENDMENT   OF   PARAGRAPH   4.C.II  OF  THE  LICENSE
                           AGREEMENT:   In  each  instance  in  which  the  date
                           "November 30, 2005" appears in Paragraph 4.C.ii, such
                           date will be replaced with October 31, 2006.

                  3.0      No Other  Amendments.  This Second Amendment shall be
                           construed as part of the License Agreement. Except as
                           specifically  amended herein,  the License  Agreement
                           shall remain in full force and effect.




         IN WITNESS WHEREOF, the Parties hereto have caused this Agreement to be
executed by their  respective duly authorized  officers or  representatives  and
signed below.

UNIVERSITY OF CHICAGO                        PHARMAFRONTIERS CORP.

By: Alan Thomas                              By:  David B. McWilliams
--------------------------------------       ----------------------------------
Name:  Alan Thomas                           Name:  David B. McWilliams
Title: Director of Technology Transfer       Title:  Chief Executive Officer
Date:  April ________, 2006                  Date:    April ________, 2006