In Japanese and other Asians, the prevalence of genetically decreased mitochondrial aldehyde dehydrogenase (ALDH2) activity is higher than in Caucasians. The aim of this study was to elucidate the relation between ALDH2 genotypes and blood pressure levels or hypertension in Japanese. After obtaining informed consent for genetic analysis from 917 men and 1,478 women who lived in a mountainous farming region near Kyoto and who were free from cardiovascular disease and liver dysfunction, the authors identified the ALDH2 genotype in all subjects. Differences in blood pressure level among genotypes were then compared by analysis of covariance, and the relation between genotypes and hypertension was also analyzed by logistic regression analysis. The frequencies of genotypes *1/*1, *1/*2, and *2/*2 were 44.7%, 46.9% and 8.4% in men, and 50.1%, 43.2% and 6.8% in women, respectively. In men, systolic and diastolic blood pressures tended to decrease in the order of *1/*1>*1/*2>*2/*2. However, adjustment for confounding factors including alcohol consumption resulted in the disappearance of significance. Logistic regression analysis adjusted for the same confounding factors for men showed that the odds ratios (OR) of being hypertensive in the *2 allele to not having *2 allele were 0.67 (95% confidence interval (CI): 0.47-0.96). However, in the subgroup analyses, this relation was not observed in the group having a below-median level of alcohol consumption (OR = 0.92; 95% CI: 0.53-1.62) or in the group not taking antihypertensive agents (OR = 0.77; 95% CI: 0.52-1.15). Furthermore, we did not observe any relation between the ALDH2/*2 allele and hypertension in women (OR = 1.07; 95% CI: 0.80-1.42). The results suggest that there may be no causal relation between hypertension and the ALDH2 genotype per se, after excluding for some confounding factors, especially for alcohol drinking.