HLA-A, -B, and -DR antigens, including supertypic specificities (MT antigens), were studied in Japanese schizophrenic patients. Although frequencies of HLA-A, -B, and MT antigens did not differ significantly between the schizophrenic patients and controls, the frequency of DRw8 in DR locus showed a statistically significant increase in the patients. The authors conclude that DRw8 is a genetic marker of susceptibility to schizophrenia. Inconsistencies in previous reports of antigens could be resolved by examination of the DR locus.