In 90 patients with typical angina pectoris, resting ECGs and cardiac catheterization findings were independently reviewed to determine whether ECG findings could be used to predict the extent of disease and the state of the left ventricular (LV) function. Thirty consecutive patients in each of three ECG groups were studied: group 1, normal ECG: group 2, ST-T abnormalities; and group 3, Q wave infarction pattern. Triple vessel disease was present in 30 percent, 40 percent, and 66 percent of patients in groups 1, 2, and 3, respectively. The ejection fraction (percent) (mean +/- SD) was 65 +/- 12, 64 +/- 11, and 51 +/- 16 in groups 1, 2, and 3, respectively. With increasing ECG abnormality (group 1 to group 3), there was a tendency to both more extensive coronary disease and greater depression of left ventricular function. However, the resting ECG appeared to correlate bettter with the state of the LV function than with the extent of the coronary artery disease.