The results of current investigation suggest that a former clinical standby, namely, the presence or absence of angina, is no longer the principal prognostic factor for determining a patient's risk of cardiac events, including myocardial infarction. In a retrospective analysis, patients with chronic stable angina were compared on the basis of presence or absence of angina during ischemia detected by thallium imaging. Patients were similar in terms of risk factors, clinical characteristics and catheterization data. At 30 months of follow-up, the myocardial infarction rate was 22% in the silent group compared with 4% in the group with angina. Transient asymptomatic ischemia has prognostic value independent of other variables such as exercise stress testing or cardiac catheterization data. Future prognostic studies should be careful to include patient populations with similar characteristics; they also will need to provide protracted follow-up and utilize sensitive and reproducible diagnostic techniques.