Sixty-two Dutch patients with the diagnosis paranoid schizophrenia (SCH) were HLA-A-, -B- and -C-typed. An increase in the frequencies of A9 (P = 0.02, relative risk 1.8) and B5 (P = 0.04, relative risk 1.9) was found. Although these correlations do not remain significant after correction for the number of antigens tested, both findings confirm other data from the literature, including the first published report from a population in Sweden. From all hitherto published literature data, the combined relative risks for A9 and B5 is significantly increased. These data strongly indicate that the distribution of HLA antigens among SCH patients is different from the control population.