An early exercise stress test was carried out in 116 patients 8 to 14 days after a myocardial infarction. This test is in good agreement with the late maximal stress test performed 8 weeks after the infarction, both tests being positive together in 86.4% and negative in 84.6% of the cases. Residual coronary insufficiency is present in 41.4% of the patients during the early test, 47.9% after inferior and 30.2% after anterior infarction. With beta blocking therapy, 28.2% of the patients had a positive test, and 48% without this treatment. The sensitivity of the early test is good after inferior infarction but poor after anterior infarction or during beta blocking therapy. A multivessel disease is disclosed by coronary angiography in 78.5% of the patients with a positive early stress test and in 53.3% in cases with a negative test. In the patients with a positive test, mortality at one year is higher (8.7% versus 2.9%). A coronary angiography should be performed relatively precociously in this group of patients.