There have been only limited reports on major histocompatibility complex class I antigens in pemphigus.To characterize HLA-A, B and C class I alleles by genotyping in Japanese patients with pemphigus, and to analyse the possible association of class I alleles with disease susceptibility within a relatively homogeneous ethnic population.Alleles of HLA-A, B and C, and DRB1 and DQB1 loci were fully determined in 51 Japanese patients with pemphigus.Asian alleles of the HLA-B15 family, including the allele B*1507, which was significantly increased in comparison with normal controls, were prevalent in patients with pemphigus vulgaris (PV). The prevalence of B*15 alleles in patients with PV was not due to linkage disequilibrium with HLA-DR4 or DR14 alleles, which have been shown to confer strong susceptibility to PV across racial barriers. In contrast to the unique distribution of the HLA-B alleles, HLA-A and C alleles were unremarkable in patients with PV when compared with normal control subjects.These results suggest that there may be differences in the ethnic concentrations of different HLA-B alleles in patients with PV.