The clinicopathological study on the atherosclerosis and cerebrovascular and cardiac complications was carried out in 1561 consecutive autopsied cases in the elderly. The subjects were classified into 3 groups: 702 cases (45.0%) of normotension, 276 cases (17.7%) of systolic hypertension and 583 cases (37.3%) of diastolic hypertension. The acceleration of atherosclerosis by hypertension was prominent in sixties and seventies, less remarkable in eighties and almost none in nineties. The effect of hypertension was remarkable on cerebral artery, aorta and coronary artery in this order, and no difference was found between the systolic and diastolic hypertension groups. On the basis of atherosclerotic changes, strokes and myocardial infarction were prevalent in both these groups in comparison with the normotension group. The difference between the systolic and diastolic hypertension groups and the normotension group was prominent in sixties and seventies, but in eighties only the diastolic hypertension group showed a significant difference with the normotension group. The effect of hypertension was more remarkable on strokes than myocardial infarction. The lack of remarkable effect of hypertension on the cases over eighty may be attributed to the progression of atherosclerosis with age in normotensive cases. The 4 year prospective trial on the effectiveness of the antihypertensive treatment was performed in 100 mild hypertensive patients of the aged, averaging 76.1 years. The matched pair group was selected by the age, sex and blood pressure. Cerebrovascular and cardiac complications were observed in 4 cases of 10.5% of 38 cases of the drug group, and in 9 cases or 22.0% of 41 cases of the placebo group. When the elevation of blood pressure over 200/110 mmHg, observed in 8 cases in the placebo group, were included as one of the cardiovascular complications, the complications in placebo group reached 41.5%, showing a significant difference. Other complications such as cancers, infections and bone or joint diseases, were observed in 12 cases or 31.6% in the drug group and in 17 cases or 41.5% in the placebo group. Blood pressure was decreased from 171/87 to 151/80 in the drug group in the 4 year period. The present study suggested that antihypertensive treatment was effective in the aged hypertension, and careful follow up was needed not only for cardiovascular complications but also for general health condition.