Abstract Sixty consecutive patients were studied who had positive responses to Naughton exercise treadmill testing (at least 1.5 mm of ST-segment shift in at least 2 leads or thallium reperfusion abnormalities) with or without symptoms of angina 11 ± 1 days after acute myocardial infarction (AMI). All patients had undergone coronary angiography 24 ± 4 days after infarction. Thirty-eight patients (63%) had no treadmill angina (silent ischemia, group I) and 22 patients had typical treadmill angina (symptomatic ischemia, group II). Use of β-blocking drugs, calcium antagonists and nitrates at the time of exercise testing did not differ in the 2 groups. All 9 patients with diabetes mellitus were in the asymptomatic group (p <0.40) and group I had a greater proportion of inferior wall AMI (30 of 38) than group II (11 of 22, p = 0.02). Total exercise treadmill test duration (group 1422 ± 31 seconds, group II 400 ± 46 seconds) and rate-pressure product were not different in the 2 groups. The number of patients unable to exercise 5 minutes (12 in group I and 7 in group II), the number with diffuse electrocardiographic changes (9 in group I and 7 in group II), and the number with inadequate blood pressure response (8 in group I and 4 in group II) were also similar. At coronary arteriography the mean number of arteries with at least 70% diameter stenosis was 2.0 ± 0.2 in group I and 2.2 ± 0.2 In group II (difference not significant). No significant difference was noted in the number of patients with multivessel coronary artery disease (74% in group I and 73% in group II). The infarct-related artery was totally occluded in 66% patients in group I and 55% patients in group II (difference not significant). Thus, asymptomatic ischemia occurs frequently in patients who undergo early post-AMI exercise treadmill testing and the exercise performance and angiographic characteristics of these patients are similar to those in patients with symptomatic treadmill ischemia.