Summary: Guinea pigs and rabbits given injections of homologous retina emulsified in Freund's adjuvant developed ocular lesions typically affecting the uveal tract. Injections of both species with heterologous retina also resulted in uveitis in some instances, depending on the species of retina used. These results were obtained by both single and repeated injections of retinal tissue. In contrast, single injections of many other homologous or heterologous intraocular tissues, including uvea itself, were ineffective in production of ocular disease. A series of repeated injections of the guinea pig with homologous uvea resulted in mild uveitis demonstrated histologically, but not clinically. Similar injections of the guinea pig with heterologous uvea were ineffective in production of uveitis, as were injections of both homologous or heterologous uvea in the rabbit. Immunization of the rabbit with homologous optic nerve elicited uveitis and encephalomyelitis which occurred simultaneously in the same animal. Similar immunization of the guinea pig resulted in encephalomyelitis only. These results were correlated with demonstration of encephalitogenic antigen in rabbit retina, but not in guinea pig retina. The interrelation and differentiation of these models of EAU are discussed.