Atrial pacing and treadmill exercise were performed by 28 patients to determine the value of each test in the clinical and functional evaluation of the patient with coronary artery disease (CAD). The functional aerobic impairment (FAI) in 20 patients was 48 percent (eight patients with unstable angina paced but not exercised) and the pacing ventricular function curve (VFC) was abnormal in 13 of these 20. Five patients with severe FA1 (pain Limited) had a normal pacing VFC. Although the FA1 was greater the more extensive the CAD, no such correlation existed between the pacing VM= and the number of d i d coronary vessels. Exercise testing does not necessarily indicate the functional performance of the left ventricle since the V& max is frequently pein limited. Atrial pacing, although less sensitive, permits a VFC determination, even in poorly motivated and no* ambulatory patients, and combined studies will indicate the patient's clinical, as well as myocardial status.