Seven hundred and seventeen hypertensive middle-aged men (HTs) were compared with 4,438 normotensive men (NTs). The association between the prevalence of hypertension and a number of demographic, physical, biochemical and electrocardiographic characteristics was examined by multiple logistic analysis. HTs were characterized by significant elevations of pulse rate, relative weight, serum uric acid, and high-density lipoprotein-cholesterol. HTs had a higher percent of major electrocardiographic findings, such as ischemic T wave changes, ST depression and, most significantly, left-ventricular hypertrophy. They were 4.7 yr older than the NTs and were more often of Central European than of Middle Eastern descent. Mortality in HTs over a 4.5-yr period was dose-response related to casual systolic and diastolic blood pressure readings at baseline. The age-adjusted HT/NT mortality ratio was approximately 2.5:1. Cardiovascular and cerebrovascular disease accounted for 69% of the total mortality among HTs as compared with 48% among NTs. The estimated mortality fraction attributable to hypertension was 23%. This figure provides an estimate for the goal of hypertension control in the community.