Serum samples from a patient diagnosed as having active Behçet's syndrome with iritis were evaluated by the enzyme-linked immunosorbent assay for antibodies against a purified bovine corneal protein, molecular weight 54,000 daltons (BCP 54). Significantly elevated antibody levels to BCP 54 were found in all serum samples collected over a 2-year period. Anti-BCP 54 antibody levels remained within a very narrow range, at least twofold higher than those of controls. In contrast, no antibody to retinal S antigen was detected. These results indicate the presence of specific anti-BCP 54 autoantibodies in sera from a Behçet's patient and suggest that autoantibodies may play a role in the etiopathogenesis of uveitis.