We examined the genotypes of ALDH2, ADH2, ADH3 and P-4502E1 loci of alcoholics and nonalcoholics. Also we compared the frequencies of the homozygous ALDH2*1/1 genotype and heterozygous ALDH2*1/2 genotypes in alcoholics. Our study reported differences in the allelic frequencies of ALDH2, ADH2 and ADH3 loci between alcoholics and nonalcoholics. For alcoholics, it was indicated that ADH2 and ADH3 plays an important role for alcoholism. For genotypes of P-4502E1, no significant difference was observed between alcoholics and nonalcoholics. Alcoholics with the heterozygous ALDH2*1/2 genotype had significantly higher frequency of the ADH2*1 than that of alcoholics with ALDH2*1/1 genotype. Concerning the alcoholics with the heterozygous ALDH2*1/2 genotype, we assumed that ADH2*1 plays a role for the development of alcoholism.