A 41-year-old woman was admitted suffering from chest pain and dyspnea. We performed an emergency operation under a diagnosis of type A acute aortic dissection combined with type B chronic 3-channeled dissection on CT scan. The ascending aorta was replaced with woven Dacron graft under deep hypothermic circulatory arrest. Atrial inflow for cardiopulmonary bypass was initiated only through the femoral artery because the right axillary artery was stenotic. Neither cystic medial necrosis nor aortitis were recognized in pathological examination of the ascending aorta. Postoperative recovery was smooth and uneventful. Three-channeled aortic dissection tends to enlarge the false lumen, and has a high risk of rupture compared with the more common 2-channeled aortic dissection, therefore careful follow-up is needed in this patient. When acute type A dissection is complicated with 3-channeled chronic dissection, it is important to preoperatively assess the route of visceral blood supply, and to carefully select the cannulation site of extracorporeal circulation to prevent malperfusion.