A total of 168 patients with different types of affective disorders were examined with respect to their HLA antigens. The frequency of the AlO antigen was found to be increased in the patients particularly in those with the unipolar type of disease. The frequency of the Al antigen was decreased among unipolar patients. A decreased frequency of the B7 antigen was found in the total material of patients, and in particular in those with a bipolar type of disease. Our results were in disagreement with findings by other investigators. So far there is no conclusive evidence for association between any HLA antigen and affective disorders.