Systolic time intervals (STI) were correlated with radionuclide angiography studies (RAS) in 57 patients at rest, during maximal semisitting bicycle exercise, and at 4 minutes following the cessation of exercise. Eleven were judged as being free of coronary artery disease (group 1), while 14 had coronary artery disease without (group 2A), and 27 (group 2B) with a previous transmural myocardial infarction. For RAS, resting radionuclide ejection fraction (REF), the changes in REF and end-systolic volume, and the development of a wall motion abnormality at peak exercise were each highly correlated with the presence of coronary disease (p less than 0.001). The accuracy of STI parameters in predicting the presence of coronary disease was poor (less than 60%). Changes in end-diastolic volume (EDV) correlated significantly with PEP/LVET and LVET1 changes following exercise. Moreover, patients with an abnormal (greater than 25%) increase in EDV at peak exercise had a greater increase in LVET1 in the postexercise period (p less than 0.01). We conclude that STI is not accurate enough a predictor of coronary disease or left ventricular function to serve as a useful screening test. Changes in STI parameters appear to be more related to changes in ventricular volume than to ventricular function.