Eighteen patients with congestive heart failure (CHF) complicating coronary artery disease (CAD) and seven patients with CHF due to primary cardiomyopathy (CM) were studied during infusions of dobutamine in doses of 2.5–15.0 μg/kg/min. There were statistically significant (p< 0.05) improvements in cardiac index, stroke volume index, left ventricular stroke work index and nuclear ejection fraction in both groups. Significant decreases (p< 0.05) in pulmonary capillary wedge pressure, right atrial pressure, and systemic and pulmonary vascular resistances were also observed in both groups. However, five patients increased an already elevated pulmonary capillary wedge pressure during dobutamine infusion, which was associated with either the development of angina pectoris or with a significant elevation of the mean arterial pressure. In the CAD patients, gated cardiac scans analyzed for segmental wall motion showed improvement in 27% of the abnormally contracting segments during dobutamine infusion. Finally, the effects of dobutamine on myocardial metabolism were assessed with arterial and coronary sinus lactate analysis. Fourteen of the 18 CAD patients (78%) showed no metabolic abnormality during dobutamine infusion; four CAD patients (22%), three of whom developed typical angina pectoris, displayed abnormal lactate metabolism. None of the CM patients developed angina pectoris or displayed abnormal lactate metabolism. Of the seven patients with an adverse hemodynamic or metabolic response, four had recently been withdrawn from propranolol therapy. In conclusion, dobutamine produced favorable effects on hemodynamics, left ventricular ejection fraction, and segmental wall motion abnormalities in most patients with CHF without a deleterious effect on myocardial metabolism.