The objective of the present study was to determine whether the presence of the classical coronary risk factors increases the likelihood of acute cardiac ischemia beyond that expected from clinical presentation and electrocardiogram. Clinical data and reports of classical coronary risk factors were collected prospectively from 1743 patients without clinically obvious coronary disease. Patients were selected from 5773 emergency department patients at 6 hospitals who presented with symptoms suggesting acute ischemia. We used logistic regression to determine the relative risk of each risk factor report for acute ischemia. In women, the presence of classical risk factor reports does not increase the risk of acute ischemia. In men, only diabetes and family history of myocardial infarction significantly increase the risk (p less than 0.05). The relative risks are 2.4 and 2.1, respectively, and are small compared to those conferred by chest pain (12.1), an abnormal ST segment (8.7), or an abnormal T wave (5.3). For a patient presenting to the emergency department, the classical coronary risk factors convey minimal risk for acute cardiac ischemia, especially when compared to the overwhelming importance of the chief complaint and the ECG.