A strong association with HLA antigens DR4, DRw53, and Bw54 has previously been reported among Japanese patients with Vogt-Koyanagi-Harada disease (VKH) and sympathetic ophthalmia (SO). In the United States, no firm association between HLA-A or -B loci and VKH has been found previously; testing for HLA-DR loci has not been performed to date. The authors performed HLA typing of 23 American patients with VKH and 8 patients with SO. When VKH patients were compared with racially matched controls without disease and patients with other types of uveitis, strong associations with HLA-DR4 and HLA-DRw53 were found. The strongest associations observed in this sample were with HLA-DQw3, an antigen which is in positive linkage disequilibrium with DR4, and with the HLA-DR4/DQw3 haplotype. The small number of patients with SO precluded statistical analysis; however, similar HLA associations were noted. The patients also were questioned regarding their ancestry. The anecdotal association of VKH with American Indian ancestry was confirmed. It appears that the ethnoracial association may be explained by HLA type. One possible explanation for identical HLA associations in two diseases with different precipitating events yet similar ocular manifestations is development of an altered immune response to exogenous microbial antigen with subsequent autoimmunity. Further definition of the genetic susceptibility to VKH and SO may help define the pathophysiology of both diseases and allow the prediction of which patients are at increased risk for SO.