To investigate the genetic factors in Koreans with leprosy, 157 unrelated leprosy patients have been typed for HLA antigens, and compared with 162 healthy controls. The patient group consisted of 124 with lepromatous leprosy and 33 with tuberculoid leprosy. HLA-A11 was found to be increased in lepromatous leprosy (p =0.0005). HLA-Aw33 was found to be increased in both lepromatous leprosy (p = 0.0002) and tuberculoid leprosy (p = 0.005). HLA-Cw5 was found to be decreased in lepromatous leprosy (p = 0.009). Frequencied of HLA-B antigens did not differ significantly between the leprosy patients and the healthy controls.