We investigated the genotype of ADH2 and ADH3 in Chinese alcoholic cirrhotics and non-alcoholics by using a polymerase chain reaction and restriction-fragment-length polymorphism. This method is non-radioactive, easy to implement with good reproducibility. In the Chinese population, the frequencies of the ADH2*1 and ADH3*2 alleles were significantly higher in the alcoholic cirrhotic patients (53%; 23%) than in the viral hepatitis cirrhotics (32%; 8%) and the gastric and/or duodenal ulcer control patients (25%; 6%). On the other hand, the gastric and/or duodenal ulcer control patients and the viral hepatitis cirrhotic patients showed similar allele frequencies for the polymorphic ADH2 and ADH3 genes. These findings suggest that the alleles ADH2*2 and ADH3*1, coding for the high-Vmax beta 2-ADH and gamma 1-ADH, respectively, may play a protective role against alcoholism in Chinese patients.