The haemodynamic affects of dobutamine (DB) (5 microgram/kg/min), isoproterenol (I) (0.02 microgram/kg/min), dopamine (DP) (5 microgram/kg/min), were studied in 12 patients with coronary artery disease randomly divided in two groups of 6 patients. In one group each patient received DB and I, in the other group each patient received DB and DP. The following parameters were measured: heart rate, aortic blood pressure, left ventricular pressure, left ventricular dp/dt, pulmonary arterial and wedge pressure, cardiac output, stroke volume, peripheral and pulmonary vascular resistances. In both groups either I and DP increased significantly heart rate whereas DB did not modifie it. DB caused a larger increase of dp/dt max and of stroke volume as compared to I and DP. These data confirm that DB possesses an inotropic effect greater than I and DP without any significant positive chronotropic effect in patients with coronary artery disease.