In 13 patients, affected by hypertrophic obstructive cardiomyopathy (HOCM) and essential hypertension, antihypertensive-efficacy and effects of a new calcium-channel blocker (gallopamil) associated with a diuretic agent (chlorthalidone) on left ventricular systolic and diastolic performance assessed by phonocardiographic methods. The results were compared to those obtained, in the same group of patients, with a selective beta-blocker (atenolol) associated with the same diuretic agent (chlorthalidone). With both therapeutic regimens a statistically significant reduction of systolic and diastolic arterial pressure was observed; both agents were able to reduce hemodynamic gradient in systole which characterize HOCM; however, the treatment with gallopamil plus chlorthalidone determined greater effects on left ventricular diastolic function as compared to the treatment with atenolol plus chlorthalidone; both treatments determined bradycardia.