Aldehyde dehydrogenase (ALDH) plays an important role in alcohol metabolism; ALDH is responsible for the oxidation of acetaldehyde generated during alcohol oxidation. ALDH is also known to oxidize various other endogenous and exogenous aldehydes. Cytochrome P-450 2E1 (CYP2E1), a liver microsomal enzyme, also metabolizes acetaldehyde and ethanol and can be induced by other inducers including acetone and ethanol. We examined single nucleotide polymorphisms (SNP) of ALDH and CYP2E1 genotypes in Korean. Restriction fragment length polymorphism (RFLP) method was used to determine ALDH and CYP2E1 SNP. Mutation in ALDH was 60% (heterozygote 46.7% and homozygote 13.3%) among 15 cases. CYP2E1 mutation was 52.7% (heterozygote 47.4% and homozygote 5.3%) among 19 cases.