A giant isolated extracardiac unruptured aneurysm of the right coronary sinus of Valsalva was detected incidentally in a 24-year-old man with clinical findings of Ehlers-Danlos syndrome. The right coronary artery was occluded at its ostial resion. Surgical correction was performed by obliterating the orifice of the aneurysm with a Dacron patch. Microscopic examination of the diseased aortic wall revealed absence of medial elastic fibers. Collective review of 19 reported similar cases revealed that reports concerning unruptured, isolated giant sinus of Valsalva aneurysm were rare, especially in young patients, and that the aneurysm of this patient was the largest.