Syphilitic aortic aneurysm is a rare lesion today. We experienced a case of huge syphilitic ascending aortic aneurysm with aortic insufficiency. Surgical correction was done by replacement of ascending aorta with woven Dacron graft and aortic valve replacement under cardiopulmonary bypass. There is no abnormality in postoperative aortography. The postoperative course was uneventful.