Chronic experimental allergic uveitis was produced in strain XIII guinea pigs following immunization to homologous uveal antigen in seven sequences at two-week intervals. By the end of the final immunization period (day 103), 13 of 19 animals demonstrated active uveal inflammation; eight of these demonstrated moderate or severe disease. After 14 months, 11 of 13 surviving animals demonstrated clinically active uveitis; a majority demonstrated severe disease. The histologic response was characterized by large sheets of lymphoid elements; in more severe reactions; these were interspersed with foci of polymorphonuclear leukocytes. Immunologic testing revealed reactions to uvea, retinovitreous, and lens extracts. The incidence of positivity of uveal antibody increased with time.