Acute and chronic hemodynamic effects at rest and during exercise of a new dihydropyridine calcium antagonist, nicardipine hydrochloride, were studied in 10 patients with chronic heart failure. Acute intravenous administration of nicardipine resulted in a significant decrease in arterial blood pressure, systemic vascular resistance, and pulmonary capillary wedge pressure. There was a significant increase in cardiac index, stroke volume index, and the left ventricular stroke work index. Cardiac index measured at peak exercise increased significantly when compared with the cardiac index obtained at peak exercise before the infusion. After 9 days of continuous therapy with nicardipine, 30 mg three times a day, a significant decrease in arterial blood pressure and systemic vascular resistance and a significant increase in the cardiac index, stroke volume index, and left ventricular stroke work index at rest were observed in response to a single oral dose of 30 mg nicardipine. Data at peak exercise were also obtained before and 2 hours after the oral administration of nicardipine. With this comparison there was a significant increase in cardiac index, stroke work index, and exercise duration. It is concluded that in this group of patients with severe chronic heart failure, nicardipine enhanced myocardial performance during rest and exercise and this enhancement is sustained after 9 days of oral therapy.