The prognostic use of myocardial perfusion imaging is reviewed in relation to both positive and normal studies. The following populations are explored: patients with known or suspected coronary artery disease, patients with postmyocardial infarction, patients undergoing noncardiac surgery, and patients with unstable angina pectoris. The prognostic value of pharmacologic stress as well as tomographic and Tc-99m-based imaging is evaluated.