Supravalvular aortic stenosis (SVAS) is an uncommon congenital cardiac anomaly. We report sudden death, occurring during exercise, of a child who had SVAS with fusion of the right coronary aortic leaflet to the supravalvular aortic ridge, resulting in a closed sinus of Valsalva except for a few pinpoint fenestrations in the dysplastic leaflet. In addition, both aortic and pulmonic valves were dysplastic and stenotic. We postulate that near total isolation of the right coronary artery ostium from the aortic lumen compromised the blood supply to the hypertrophied ventricles. We emphasize the importance of other cardiac anomalies associated with SVAS as well as the development of coronary insufficiency.