A significant association between elevations of serum gamma-glutamyl transpeptidase (y-GTP) levels and those of blood pressure and hypertension has been reported separately in drinkers and nondrinkers. The aim of the present study is to evaluate whether the relationship between serum y-GTP and the prevalence of hypertension is the same or similar in both drinkers and nondrinkers. The study subjects comprised 4,920 male nondrinkers, 9,390 male daily drinkers, 8,081 female nondrinkers, and 278 female daily drinkers, who were aged 40 to 59 years. The prevalence of hypertension in the male and female daily drinkers was 1.5 and 1.3 times, respectively, higher than in the nondrinkers. Mean systolic blood pressure in the male and female drinkers was 4.4 and 3.1 mmHg, respectively, higher than in the nondrinkers. After adjusting for age, body mass index, and serum y-GTP levels, the differences in the prevalence of hypertension and the mean systolic blood pressure level between the drinkers and nondrinkers decreased to 1.2 times and 2.7 mmHg, respectively. Although these small differences remained statistically significant, the association between serum y-GTP and hypertension appears to be quite similar in both drinkers and nondrinkers, suggesting that hepatic steatosis may play a common, pathogenetic role in the development of hypertension. (Hypertens Res 1995; 18: 295-301)