The prognostic value of the left ventricular ejection fraction(EF) was compared to that of other commonly used indices--severity of coronary artery disease, left ventricular end-diastolic pressure, cardiac index, and abnormal ECG--in 144 patients with coronary artery disease followed for an average of 14 months on medical management. During this period, 14 patients (10%) died. Analysis of the mortality demonstrated that the EF was the most powerful predictor of short-term survival. Thus, patients with three-vessel coronary artery disease and anormal EF (greater than 0.50) had a significantly lower mortality (12%) than did patients with three-vessel CAD and a reduced EF (33%, P less than 0.001). Similar comparisons were observed within the subgroups with abnormal hemodynamics or an abnormal ECG. Therefore, the EF appears to be an important prognostic guide in the medical therapy of coronary artery disease, and is of significantly more discriminant value than other measurements when combined abnormalities exist.