BACKGROUND: Human leukocyte antigen (HLA) genotypes in lamotrigine -induced (LTG-induced) cutaneous adverse drug reactions (cADRs) have been described in several reports but controversy remains even for a given ethnic group. We attempted to clarify a possible association between LTG-induced cADRs and HLA alleles in Japanese patients. METHOD: Sixteen subjects, including eight patients with LTG-induced cADRs and eight LTG-tolerant controls were included in this study. All eight patients with LTG-induced cADRs gave positive results in a drug-induced lymphocyte stimulation test (DLST) with LTG. We performed HLA-typing for HLA-A, -B, -C, -DRB1, -DQA1, -DQB1, -DPA1 and -DPB1, using PCR with sequence-specific oligonucleotide probes and multiple analyte profiling (xMAP) technology (Luminex System; Luminex Corporation, Austin, TX). We examined differences between allele frequencies in our two groups of subjects and the allele frequencies in the general Japanese population. RESULTS: The frequencies of HLA-DRB1*0405, and HLA-DQB1*0401 alleles were higher in our LTG-cADRs patients than the reference frequencies in the general Japanese population. We also detected HLA-DQA1*0303 frequently in our LTG-cADRs patients, but data for this allele in the Japanese population was not available. Our observation was presumably due to the linkage disequilibrium among the three alleles. The haplotype frequency of HLA-DRB1*0405, DQB1*0401 and DQA1*0303 in our LTG-cADRs subjects was also different from the corresponding haplotype frequency in the database for the Japanese population and the difference was statistically significant. One patient with the HLA-DRB1*0405, -DQB1*0401 and DQA1*0303 haplotype was safely re-treated with LTG after results of a DLST with LTG ceased to be positive about 4 months after discontinuation of LTG. LIMITATIONS: Our analysis included only 16 patients. Associations between LTG-induced cADRs and specific HLA loci will have to be confirmed in larger studies. CONCLUSIONS: LTG-induced cADRs are associated with HLA-DRB1*0405, -DQB1*0401 and -DQA1*0303.