X0202 3 2006-04-13 0 0001069308 PharmaFrontiers Corp. PFTR 0001044321 MARXE AUSTIN W & GREENHOUSE DAVID M C/O SPECIAL SITUATIONS FUNDS 527 MADISON AVENUE, SUITE 2600 NEW YORK NY 10022 0 0 1 0 Common Stock 9716000 I By Limited Partnerships Warrants 0.65 2006-04-13 2011-04-13 Common Stock 4858000 I By Limited Partnerships This is a joint filing by Austin W. Marxe (Marxe) and David M. Greenhouse (Greenhouse). They share voting and investment control over all securities owned by Special Situations Fund III QP, L.P. (QP), Special Situations Cayman Fund, L.P. (Cayman), Special Situations Private Equity Fund, LP (PE) and Special Situations Life Sciences Fund, L.P. (LS), respectively. 3,310,000 shares of Common Stock & 1,655,000 Wts are held by QP, 906,000 shares of Common Stock and 453,000 Wts are held by Cayman, 4,000,000 shares of Common Stock & 2,000,000 Wts are held by PE and 1,500,000 shares of Common Stock & 750,000 Wts are held by Tech II. The interest of Marxe and Greenhouse in the shares of Common Stock & Warrants owned by QP, Cayman, PE, and LS is limited to the extent of his pecuniary interest. Austin W. Marxe 2006-04-24 David M. Greenhouse 2006-04-24