The predictive value of exercise stress testing was assessed by correlating the results with coronary angiography in a group of 100 patients 50 with inferior and 50 with anterior wall infarction. The following observations were made: --The exercise ECG was positive in 57 p. 100 of cases, more commonly in the inferior infarction group (74 p. 100), ST depression representing over 3/4 of the responses to exercise. On the other hand, the test was only positive in 40 p. 100 of anterior wall infarctions, ST depression again being the most commonly recorded response (65 p. 100). --The overall incidence of post-infarction angina was 45 p. 100; it was more common after inferior (70 p. 100) than anterior infarction (22 p. 100). --Multivessel disease was also more severe in the inferior infarction group (86 p. 100) than in anterior infarction (46 p. 100). However, ventricular aneurysms were twice as common in the anterior infarction group. --Exercise testing detected 80 p. 100 of cases with multivessel disease, especially when the LAD artery was involved, in the inferior infarction group. In the anterior infarction group, almost 50 p. 100 of patients with multivessel disease were not diagnosed. Despite an overall sensitivity of 73 p. 100 the predictive value of exercise stress testing was excellent (84 p. 100). In conclusion, in the presence of persisting angina after myocardial infarction coronary angiography should be performed to determine the severity of the multivessel disease. Exercise stress testing is a useful but imperfect method of detecting this high risk group. Its predictive value is however better in inferior (94 p. 100) than in anterior wall infarction (65 p. 100). Persisting angina was found to be a parameter of very high specificity (100 p. 100) for the presence of multivessel disease.