The effect was studied of 8 weeks of treatment with propranolol and pindolol on the left-ventricular myocardium mass, left-ventricular myocardium mass index, plasma renin activity, and serum aldosterone and total catecholamine concentrations. The studies were carried out in 72 patients with essential arterial hypertension of slight degree. A statistically significant decrease was shown of the left-ventricular myocardium mass, left-ventricular myocardium mass index, plasma renin activity, and aldosterone concentration in all studied patients. A decrease of total catecholamine concentration appeared in patients treated with propranolol. Weaker effect of pindolol on the studied parameters may be connected with its intrinsic sympathicomimetic activity. A correlation was shown between the decrease of the left-ventricular myocardium mass, and the decrease of systolic arterial blood pressure.