In a prospective study of cardiovascular findings in 57 patients with acromegaly, hypertension was found in 13. As a group, the hypertensives were older, had their acromegaly longer, and had higher plasma growth hormone concentrations. Typically, the hypertension was mild, uncomplicated, and responsive to drugs. Irrespective of blood pressure, nine patients had symptomatic heart disease, including four with arrhythmias, of whom three had hyperthyroidism. Seven of the nine patients had congestive heart failure, including two with coronary heart disease, two with cardiomyopathy, and two with arrhythmias. Cardiomegaly, although uniformly present at necropsy, was detected clinically only in patients with hypertension or congestive heart failure. In this series we were unable to measure the incidence or prevalence of cardiac disease in acromegaly, to detect a characteristic form of heart disease in acromegaly, or to define a clear relation between cardiac disease and the plasma growth hormone concentration.