Human leukocyte antigens (HLA) class II alleles were analyzed among Japanese leprosy patients to ascertain whether immunogenetic differences exist among the leprosy classification forms of Ridley and Jopling. Ninety-three unrelated Japanese leprosy patients (21 lepromatous, 24 borderline lepromatous, 17 mid-borderline, 26 borderline tuberculoid, 5 tuberculoid) and 114 healthy control subjects were investigated. The frequencies of HLA-DRB1*1501, -DRB5*0101, -DQA1*0102 and DQB1*0602 were significantly increased in all of the Japanese leprosy patients. The frequencies of HLA-DRB1*0405, -DQA1*03 and -DQB1*0401 were significantly decreased in the Japanese patients after correction of the p value. Conversely, there were no significantly different distributions of the HLA-DRB1, -DRB5, -DQA1, DQB1 alleles in the five subgroups of these patients. We conclude that HLA class II alleles were not associated with the form of leprosy. Other HLA, a non-HLA gene, and/or environmental factors may play a critical role in the different manifestations of leprosy.