The aim of this study was to determine whether there is any association between interleukin-1 receptor antagonist (IL1-Ra) genotype and alcoholic liver disease. The IL1-Ra genotype was assessed in 102 Japanese male alcoholic liver disease patients and 46 healthy subjects by polymerase chain reaction with leukocyte DNA. The distribution of IL1-Ra genotype and the allelic frequencies in Japanese healthy subjects are both significantly different from that previously reported in Caucasians (A1/A1 genotype: 95.7% in Japanese vs. 54.0% in Caucasians, p < 0.001; A1 allele: 97.8% vs. 73.4%, p < 0.001). The frequency of A1 heterozygotes tended to be higher in Japanese alcoholics with fibrosis, compared with those without fibrosis (14.9% vs. 2.9%). Furthermore, within the fibrotic groups, cumulative alcohol intake was significantly lower in A1 heterozygotes than in the A1 homozygotes (877 +/- 118 kg vs. 1369 +/- 90 kg,p < 0.05). In conclusion, a genetic polymorphism in the IL1-Ra gene may influence the risk of developing hepatic fibrosis in Japanese alcoholics. The same study should be conducted in Caucasian patients having more frequency of IL1-Ra A1 heterozygotes.