Reports concerning unruptured, isolated aneurysms of one sinus of Valsalva are rare. These aneurysms usually protrude inside the heart and are very rarely extracardiac. We report 4 cases of isolated, unruptured extracardiac aneurysms of the noncoronary sinus of Valsalva. Clinical symptoms were nonspecific. Operation was performed by patch reconstruction of the dilated aortic sinus without replacement of the ascending aorta. Microscopic examination of the diseased aortic wall revealed absence of medial elastic fibers. Late follow-up in all 4 cases revealed a normal ascending aorta with no dilatation of the aortic root and no aortic regurgitation.