The authors report on the case of a 10 year-old girl who died suddenly after exercise. The autopsy showed abnormal origin of the left coronary trunk from the right sinus of Valsalva, with proximal course of the vessel between the aorta and pulmonary trunk. We discuss on the mechanism of myocardial ischemia; the opportunity to diagnose such an anomaly when the patient is alive is rare, and cause of death is most frequently determined by necropsy.