A 72-year-old woman was admitted as an emergency case to our hospital because of chest oppression. She had a history of admission due to the same symptoms about 9 months previously. Her chest computed tomography showed a dissection of the ascending aorta (DeBakey type II). We suspected an acute aortic dissection and an emergency operation with CPB was performed. The ascending aorta was markedly enlarged, but the dissected adventitia did not appear weakened. Moreover, there was no bloody pericardial effusion which is specific to acute aortic dissection. When the pseudo-lumen was exposed, a firm intimal flap and single entry hole were recognized. The chronic phase of aortic dissection was finally diagnosed. Then the dissected adventitia and intimal flap were removed and a patch graft aortoplasty with a tailored 26mm gelatin-impregnated knitted Dacron vascular graft was employed because the residual aortic wall was normal in size and consisting. Her postoperative course was uneventful and there was no evidence of recurrence of aortic dissection or enlargement 2 years after the operation. We conclude that patch aortoplasty for repair of chronic aortic dissection can be effective when the range of dissection is restricted and to residual aortic wall is normal.