Lens-induced granulomatous uveitis was produced in brown Norway rats. To determine the role of the lipoxygenase and cyclo-oxygenase products of arachidonic acid in the modulation of granulomatous uveitis, one group of experimental animals was treated with nafazatrom, while another group was treated with nordihydroguaiaretic acid (lipoxygenase inhibitors). Both resulted in significant attenuation of granulomatous inflammation, with reduced giant-cell infiltration into the choroid. In contrast, indomethacin (a cyclo-oxygenase inhibitor) therapy resulted in increased giant-cell formation. These findings suggest that the lipoxygenase and cyclo-oxygenase products of arachidonic acid play a role in the development of granulomatous uveitis and that such inflammation can be selectively suppressed by lipoxygenase inhibitors.