The prognostic value of abnormalities resulting from predischarge submaximal treadmill exercise testing was evaluated in 222 patients after myocardial infarction. The presence of the following variables--ST segment depression and elevation, an abnormal blood pressure response, limited exercise duration, angina pectoris, ventricular arrhythmias--were predictive of subsequent cardiac events (P less than 0.001) among the 154 patients with one or more of these abnormalities. When the presence or absence of specific variables was assessed, only an abnormal blood pressure response, limited exercise duration (P less than 0.001), and ST segment elevation and shift (P less than 0.05), were significantly associated with cardiac death. Exercise-induced angina was predictive only of the development of subsequent angina (P less than 0.05), and ST depression was associated only with future coronary surgery (P less than 0.01). Ventricular arrhythmias had no independent prognostic value. Markers of left ventricular dysfunction elicited by submaximal exercise testing are therefore valuable in identifying patients at high risk of death after infarction. Hallmarks of residual reversible myocardial ischaemia are of limited prognostic importance. The test result may be useful in selecting patients for coronary angiography.