This case report presents a marathon runner who was diagnosed with coronary artery disease. We discuss the issue of evaluation of such patients with respect to continuation of competitive physical activity. The reported case shows that continued training involving above class IA-IIA sports is possible (however, long-distance running as well?) if a subject with single vessel disease after an effective PCI maintains close contact with his/her doctor and obeys the rules of safe training. On the other hand, it supports the thesis that regular working out, even in professional athletes, does not guarantee 'healthy' coronary arteries.