In order to investigate the cause of heart failure in hypertension the hearts of forty hypertensive patients who died with symptoms of myocardial insufficiency were studied. As a control group thirty hearts from patients with hypertension who died of cerebral accidents, renal insufficiency, or incidental disease were likewise studied.

Thirty-four (85 per cent) of the cases in the cardiac group had significant coronary arterial involvement (sclerosis or thrombosis), whereas only three (10 per cent) of the cases in the control group had significant coronary artery disease.

The myocardial changes in both groups reflected roughtly the extent and degree of coronary artery involvement.

In six (15 per cent) of the forty cardiac cases there was not sufficient organic change in the coronary arteries or myocardium to account for the heart failure. Three of these six patients had marked pulmonary complications. Theories seeking to explain the cause of the heart failure in the remaining three cases are reviewed.