Dissecting aortic aneurysm is relatively rare in those under 40 years of age without high risk factors. After dissecting aortic aneurysm is occurred, the coronary artery is rarely perfused by false lumen. We present a thirty two-year-old man who showed Debakey type 1 dissecting aortic aneurysm with right coronary artery perfused by false lumen of ascending aorta and with congestive heart failure due to aortic insufficiency without discernible risk factor. Medical and surgical treatment (Modified Bentall's operation) were successfully performed. The pathologic report showed combined cystic medial necrosis. Now he is well tolerated and stable only with anticoagulation during follow up 18 months.