Echocardiography was used to evaluate cardiac anatomy and function in 25 patients with acromegaly. Eighty per cent of the patients (20 of 25) had abnormal echocardiograms including 13 patients without other signs or symptoms of cardiac involvement. The most common abnormality was increased left ventricular mass with concentric left ventricular wall thickening, which was found in 64 per cent (16 of 25) of the patients. Increased left ventricular transverse dimension at end diastole was found in 36 per cent (nine of 25) of the patients. Other echocardiographic abnormalities found included left atrial or aortic root enlargement (three patients), disproportionate septal thickening (one patient) and depressed left ventricular ejection fraction (three patients). Since five of the patients with increased left ventricular mass had no history of hypertension or hyperthyroidism, the increased mass cannot be ascribed solely to these conditions commonly associated with acromegaly. Furthermore, the degree of cardiac hypertrophy showed no significant correlation with pre- or post-treatment growth hormone levels, or with known duration of acromegaly prior to treatment. Thus, although the pathophysiology and significance of cardiac abnormalities in acromegalic patients is not yet fully understood, echocardiography does provide a sensitive tool for detecting such abnormalities before they are otherwise apparent. © 1979.