The hemodynamic effects of acute alcohol intoxication were studied at rest and during upright exercise in 28 patients with coronary artery disease by right-sided heart catheterization and radionuclide cardiography. The mean arterial blood pressure at rest was reduced by 5% and the left ventricular ejection fraction at rest decreased 2% because of end-systolic dilation during intoxication (serum ethanol 21 mmol/liter). No changes were observed in heart rate, stroke volume, pulmonary artery pressure, pulmonary artery wedge pressure or total peripheral resistance. No significant changes occurred in plasma catecholamines, and no changes occurred in any variable during mild exercise corresponding to a 30 to 40% heart rate increase. Thus, alcohol ingested in moderate doses causes slight impairment of left ventricular emptying and a reduction in the arterial blood pressure at rest in patients with coronary artery disease. A mild exercise load can be tolerated during alcohol intoxication without hemodynamic changes.