A 52 year-old man underwent aortic valve replacement and ascending aortic replacement (Wheat procedure) for acute dissection (Stanford type A) and aortic regurgitation (grade 3/4). At that time, the aortic root was slightly dilated at about 45 mm and the descending aorta was within a normal range at about 35 mm. Forty months after the initial operation, a follow-up chest enhanced computed tomography showed an aortic root aneurysm about 60 mm in diameter, a thoracic aortic aneurysm about 70 mm in diameter and chronic aortic dissection. First we performed the Bentall procedure, innominate artery and left common carotid artery replacement by 12 mm, and 10 mm Hemashield grafts during selective cerebral perfusion. After 10 weeks, we carried out aortic arch, descending aorta and left subclavian artery replacement. The postoperative course was uneventful and postoperative examination demonstrated a good surgical result. Histological findings of the aortic aneurysm wall showed cystic medial necrosis, but Marfan's syndrome was excluded clinically. We could diagnose aortic root aneurysm by regular follow-up chest enhanced computed tomography (CT) and echocardiography. Therefore, cases with slight dilation of the aortic root in the Wheat procedure should undergo regular follow-up evaluation by chest enhanced CT and echocardiography.