The prognostic value of electrocardiographic tracings was investigated in the course of annual physical examinations of 756 business executives who had no history or symptoms suggestive of coronary heart disease. The age range was from 23 to 74 years. Electrocardiograms were obtained in each patient after the double Master twostep exercise test. The number of patients having abnormal electrocardiographic patterns when first examined was 280, and, of these, 32 later developed coronary artery disease. The remaining 476 had normal tracings, and only 20 developed coronary disease. The significant findings concerned the ischemic type of response pattern, which was found on 23 of the initial tracings. Sixteen (70%) of these patients later developed coronary artery disease. This finding is significant in view of published data on patients with known coronary disease, which show that 61.3% develop the ischemic pattern after the Master two-step test.