Inherited deficiency of acetaldehyde dehydrogenase type I (ALDH-I) was found in 43% (50/117) of normals, 33% (27/82) of schizophrenics, but only 4% (5/113) of alcoholics among Japanese. The ALDH-I deficiency was never found, however, in 146 mostly schizophrenic subjects from Europe (Basel, Moscow, Zagreb), Australia (Nedlands), India (Lucknow), Morocco (Casablanca) and Mexico (Mexico City). It was demonstrated that ALDH-I deficiency produces the flushing syndrome which inhibits the development of drinking habit and alcohol dependence syndrome.