Postoperative paraplegia complicating with type A dissection is extremely rare. We describe a case of acute paraplegia after emergency graft replacement of the ascending aorta for type A dissection. A 63 year-old hypertensive man presented to hospital with chest pain. A chest computed tomography demonstrated an aortic dissection of the ascending aorta with mild pericardial effusion. Under deep hypothermic circulatory arrest with concomitant antegrade selective cerebral perfusion, the ascending aorta was replaced. The patient regained consciousness six hours after operation, however, he was complicated with paraplegia. All sensation was lost below the level of Th12. The cause of the paraplegia was assumed to be a thrombotic occlusion of costal arteries, which originated from the false lumen. Spinal fluid was drained for three days. Hyperbaric oxygenation therapy was started four days after onset of paraplegia. Fortunately, our patient recovered gradually, and he was doing well and was walking independently at one-year follow-up. (Ann Thorac Cardiovasc Surg 2003; 9: 330-3)