To determine whether exercise testing performed soon after myocardial infarction may predict the degree of coronary artery disease, 78 patients performed stress testing and coronary angiography 15 +/- 5 and 64 +/- 35 days, respectively, after myocardial infarction. Out of 34 patients with a positive test, 22 (65%) demonstrated a multivessel disease, and 37 (84%) out of 44 patients with a negative test had normal coronary angiograms or single vessel disease (p = .0006). In addition to stress testing, no clinical parameter considered (infarct location, heart failure and cardiomegaly) was predictive of the extent of coronary artery disease.