We conducted a cross-sectional study to investigate the relationship between psychological load and blood pressure using white-collar male employees of a company located in an urban area in June, 1991. Excluding those with diseases which might induce hypertension or those under 20 yr and over 60 yr of age, 570 male subjects were eligible for analysis. Logistic regression analysis was applied to 461 subjects excluding 109 who showed unstable blood pressure level; the dependent variable was blood pressure class which contained 386 normotensives and 75 hypertensives. The explanatory variables were age, obesity, alcohol intake, cigarette smoking, habitual physical exercise, all well-known factors affecting blood pressure level, working time, commuting time, paid annual leave, and type of living (with family or alone) as objective workload, and Karasek's job strain as psychological workload. Odds ratio of job strain was statistically significant after adjusting for the foregoing factors, but in the case of high job strain, the prevalence of hypertension was low. Theorell has pointed out that contrary to the usual recognition those having a family history of hypertension tended to have a non-complaining life attitude and this indication seems to be the reason for the results of this analysis. Blood pressure is one of the most important problems in the field of industrial health and because of our highly industrialized society, it is necessary to consider psychological workload. Longitudinal observations which take into account psychological workloads must be planned, and personal traits represented by a family history of hypertension should be always taken into consideration.