The genotype of the CYP2E1 loci in 36 alcoholic and 42 non-alcoholic (healthy) Japanese were investigated to examine the relationship between the polymorphisms of CYP2E1 (C/D) and the susceptibility to alcohol dependence. There was a significant (df = 1, chi 2 = 4.39, p < 0.05) difference in CYP2E1 CD (heterozygote) genotype frequency between alcohol dependents (56%) and controls (33%), suggesting that the CD (heterozygote) genotype of CYP2E1 may have something to the risk of developing alcoholism in Japanese, whereas DD (homozygote) genotype was high among controls.