Ten patients with congestive heart failure underwent noninvasive and invasive hemodynamic testing before and sequentially after the administration of ibopamine to determine the cardiovascular effects of this oral dopamine congener. Single doses of 200, 400 and 600 mg were administered to all patients and 5 repeated doses of 200 or 400 mg were studied in 8. Hemodynamic effects occurred as early as 30 minutes and lasted up to 4 hours after dosing. In general, ibopamine elicited statistically significant dose-related increases in cardiac output and reductions in the derived resistance of the systemic and pulmonary circulations. A biphasic response in central and peripheral pressures was observed; up to 1 hour after administration, ibopamine elevated mean right and left atrial pressures and pulmonary and systemic arterial pressures with a significant reduction of these measurements beyond 1 hour. It did not alter heart rate. Repeated doses qualitatively affected hemodynamics similar to the initial dose and did not appear to be accompanied by short-term tolerance. While oral ibopamine elicits some favorable hemodynamic effects in humans with cardiac failure, the biphasic hemodynamic response is generally undesirable in the majority of these patients.