Various diseases with a noticeable autoimmune component and frequent occurence within one family show a statistically significant correlation with specific human leucocyte antigens (HLA). This correlation was also found in studies of HLA in psychiatric disorders. However, results have been contradictory. The phenotype frequencies of HLA specificities were investigated in 100 schizophrenic patients and 472 controls from the same geographic area in Germany. The frequency of HLA-B27 was significantly increased in the patient group as a whole and in the subgroups of paranoid patients, chronic schizophrenics, patients with poor prognosis and in patients with the onset of the disease before the age of 20 years. In the latter three subgroups an elevated incidence of HLA-A9 was also found. The combination A9-B27 was detected in 0,63% of our control group and in 7% of the patients. Of these patients 85,7% were chronic paranoid patients with poor prognostic features. The present study indicates a possible marker of genetic heterogeneity in schizophrenia and gives support to the possibility of using HLA typing in genetic studies of schizophrenia as well as in the differential diagnosis and prognosis. Moreover, in spite of the statistical significance of our findings, the fact that the associations are well below 100% indicates that other factors (presumably environmental) must be involved in the ethiology of the disease.