Background. An initial prevalence survey of mental disorders among 993 subjects aged 15 and above randomly drawn from four major Taiwanese aboriginal groups (the Atayal, Ami, Bunun and Paiwan) was conducted from 1986 to 1988. The incidence of alcoholism was investigated in a follow-up survey from 1990 to 1992.

Methods. Both surveys employed a semi-structured clinical interview with satisfactory reliability for case identification, and DSM-III-R as the diagnostic criteria for alcohol use disorders. The estimation of incidence rates of first onset alcoholism (alcohol abuse or dependence) was based on person-years at risk of 499 subjects who did not have any lifetime diagnosis of such morbidity at phase I.

Results. The follow-up rate was 99·6% and only four subjects among the survivors were not found. The age-standardized annual incidence rates of alcoholism ranged from 2·8 to 4·9% among the four aboriginal groups, and the rank order of rates was consistent with that of prevalences among these groups. The incidence rates of alcoholism were the highest among adolescents and young adults in men, and among the middle-aged in women.

Conclusions. High rates of first onset alcoholism among the Taiwanese aborigines indicate an interaction of sociocultural and biological factors in the development of such morbidity.