Carbamazepine (CBZ) is frequently used for treating epilepsy, but this drug causes cutaneous adverse drug reactions (cADRs) that may range from mild to severe. It is reported recently that the human leukocyte antigen HLA-B*1502 is associated with Stevens-Johnson syndrome (SJS) induced by CBZ in Han Chinese. We examined HLA class I in 15 Japanese patients who fulfilled the diagnostic criteria for CBZ-induced cADRs (mild in 10 and severe = SJS in 5). HLA-B*1518, HLA-B*5901 and HLA-C*0704 alleles showed higher relative risks (above 10.0) for severe cADRs. The haplotype (HLA-A*2402-B*5901-C*0102) had high relative risk (16.09) for severe cADRs. In patients with severe cADRs, frequencies of HLA-A*1101, HLA-A*3303, HLA-B*1501, HLA-B*4403, HLA-B*5101, HLA-B*5201, HLA-C*0702, and HLA-C*1202 alleles are relatively lower than in the Japanese population. These data may suggest that HLA-B*5901 is one of the candidate markers for CBZ-induced SJS in Japanese.