We report the case of an adolescent who was presented with long-standing exertional symptoms, and was diagnosed with an anomalous right coronary arterial origin arising above the commissural junction between the left and right aortic sinus, with inter-arterial and intramural compression. The precise origin of this lesion outside the aortic sinuses is unusual, and multi-detector computed tomography gave excellent definition and spatial resolution of the anomalous origin and course. It is crucial to have a high index of suspicion of exertional symptoms, as sudden death may be the first manifestation of an anomalous coronary artery.