A total of 789 Japanese male transport service workers between the ages of 35 and 50 were used as subjects in an analysis of daily lifestyle factors related to hypertension. Multiple logistic analysis showed positive dose-response relations between hypertension and age, obesity and alcohol consumption. Age and obesity were factors having a linearly increasing odds ratios for hypertension (including borderline cases and those under treatment). Alcohol consumption of 56 g ethyl alcohol per day or more had an odds ratio about double that of those who did not drink. Smokers had 1/2 the odds ratio of non-smokers. Subjects working a 24-hr shift comprised mostly of standby duty showed a slightly lower rate of hypertension, but it was statistically insignificant.