To determine the effects of ibopamine on hemodynamic parameters, 9 patients with cardiac dilation after acute myocardial infarction were studied. Although there were no significant changes in mean blood pressure, heart rate and rate pressure product after administration of ibopamine, cardiac index and urine volume increased significantly. These data indicate that ibopamine exerts a positive inotropic effect on the myocardium and vasodilating effect on renal vasculature without increasing myocardial oxygen consumption. However, pulmonary capillary wedge pressure increased significantly at 30 min after ibopamine and decreased to the control value at 120 min. A significant increase in heart rate was observed in 3 patients which was followed by chest pain. In addition to increase in cardiac contractile force and decrease in subendocardial perfusion from elevated left ventricular end diastolic pressure, increase in heart rate would decrease diastole time, while increase in oxygen consumption results in aggravation of ischemia especially in patients with multivessel coronary disease. From these findings it is considered that ibopamine should be administered with care to patients with multivessel coronary disease.