330 patients were admitted to the intensive care unit of our hospital from January 1985 to December 1986. 141 of the 150 patients aged below 65 years underwent symptom-limited maximal exercise testing on a bicycle ergometer before discharge. No severe complications were noted. 61 of those tested showed a pathological reaction such as angina pectoris, ST-segment depression or ventricular ectopic activity (couplets, ventricular tachycardia). Coronary angiography was performed in 33 patients (23.4%). The outcome of this examination led to coronary bypass surgery in 15 cases and to PTCA in 2. For 9 of these 17 patients exercise testing soon after myocardial infarction was the essential investigation that led to angiography and surgery. Symptom-limited exercise testing before discharge is a safe method of distinguishing patients at risk, requiring further investigations for possible coronary bypass surgery, from those that do not need additional work-up. We conclude that every post-myocardial infarction patient should be exercise-tested before leaving hospital.