On the basis of echocardiographic investigations changes were analysed of certain haemodynamic parameters in 40 patients aged 21-50 years, mean 44 years, with primary arterial hypertension in stage II according to WHO classification. All patients were randomly chosen to receive for 6-9 weeks propranolol 120-480 mg daily, mean dose 280 mg, or pindolol 10-35 mg daily, mean dose 22 mg daily. The changes developing during the treatment with both drugs in relation to the initial values included the mean arterial blood pressure, the heart rate, the index of cardiac output and the systolic left-ventricular tension. In the studied patients treated with propranolol the heart rate and the ejection volume were decreased more than during pindolol treatment. Propranolol increased evidently the total peripheral vascular resistance and decreased the ejection fraction and the mean velocity of shortening of the circumferential fibres. Pindolol decreased slightly the peripheral vascular resistance and increased the ejection fraction and the mean velocity of shortening of the circumferential fibres. Pindolol, in relation to propranolol, had a more favourable effect on haemodynamics in patients with primary hypertension.