The effects of cyclooxygenase inhibitors flurbiprofen and indomethacin on the inflammatory response and immune reactions induced by S-antigen in the rat eye were studied. The treatment with flurbiprofen and indomethacin administered subcutaneously every 12 hours, commenced on the day of S-antigen injection and was continued until the termination of the experiment (12 days). Flurbiprofen reduced vasodilation and the inflammatory exudate into the anterior chamber by 38% and 36% respectively while inhibiting polymorphonuclear leukocytes infiltration by 57% without affecting monocytes infiltration. Indomethacin had similar but greater effects than flurbiprofen on all these parameters. However, the differences between the mean values of the two compounds were not significant. Both compounds also attenuated spleen cell proliferation, serum IgG levels to S-antigen and interferon-gamma levels in the aqueous humor. The level of prostaglandin E2, but not of leukotriene B4, was increased in the untreated inflamed uveal tissues and this increase was significantly inhibited by flurbiprofen and indomethacin. The results of this study suggest that cyclooxygenase products are involved in the normal development of both humoral and cellular immune response in the experimental uveitis.