Since the cardinal hemodynamic disorder in essential hypertension is an increased total peripheral resistance, drugs that can lower resistance without reducing blood flow would be particularly useful. The calcium antagonists seem to fulfill this criterion. The purpose of this work was to study the hemodynamic effects at rest and during exercise of three calcium channel blockers, verapamil, nifedipine, and nisoldipine, in patients with mild to moderate essential hypertension. Fifty-four patients aged 20–64 years with pretreatment diastolic blood pressures of between 95 and 120 mm Hg were studied at rest and during exercise on an ergometer bicycle. Blood pressure was recorded intraarterially and cardiac output was measured by Cardiogreen. After the initial study, 10 patients were treated with verapamil (40–80 mg three times daily), 15 with nifedipine (long-acting form, 20–80 mg daily), and 19 with nisoldipine (10–40 mg daily). After 1 year the hemodynamic study was repeated. The immediate response to the first dose was studied in the patients taking nisoldipine and in 10 patients after taking placebo tablets. Placebo induced no significant changes in central hemodynamics during the first 3 h after tablet intake. The calcium antagonists induced a reduction in blood pressure and in total peripheral resistance (in the order of 10–18%) without any reduction in cardiac index. Reflex tachycardia and an increase in cardiac output were seen in the first 2 h after the first dose of nisoldipine, but after 1 year the heart rate was unchanged compared with the pretreatment rate at rest and during exercise. In contrast, heart rate was reduced on verapamil treatment, particularly during exercise (about 10% of patients), but this was compensated for by an increase in the stroke volume. The hemodynamic profiles of the three calcium channel blockers were slightly different, especially with respect to the heart rate response. Total peripheral resistance was reduced, acutely as well as chronically, and no depression in cardiac pump function was seen, either at rest or during exercise.