The role of macrophage migration inhibitory factor (MIF) in the regulation of ocular autoimmune disease was studied in experimental autoimmune uveoretinitis (EAU) in rats following immunization with a retinal antigen (Ag), interphotoreceptor retinoid-binding protein (IRBP). LEW rats were immunized with a single injection of IRBP derived peptide, R16(ADGSSWEGVGVVPDV). A neutralizing monoclonal antibody (mAb, IgM) to MIF was injected intraperitoneally every second day from day 0 to day 6 (group A), or from day 8 to day 14 (group B). Control rats were treated with unrelated mouse IgM or PBS. T cell proliferative responses were measured 12 days after immunization. The occurrence and severity of EAU were observed and compared among experimental and control groups. T cell proliferative responses against R16 were inhibited in rats treated with anti-MIF mAb compared with the control rats. The development of EAU was delayed in the rats of group A in comparison with those of group B and the control group. The mean histological EAU score on day 18 in group A was 1.11 ± 0.11 and significantly lower than those of the group B (1.29 ± 0.19) and the control (1.67 ± 0.19). The present result suggests that MIF plays an important role in induction of EAU.