Background : Long-term prognosis and evaluation of clinical outcome of AD(aortic dissection) and IMH(intramural hematoma) according to therapeutic decision is not well characterized. The purpose of this study is to elucidate the difference between clinical outcome of AD an IMH, and between medical and surgical treatment of them. Method : 104 consecutive patients with AD were included in this multi-center trial between January 2005 and December 2006. Data were retrospectively collected from the hospital medical records. The clinical features, result of CT followed up, treatment modalities, and survival of these patients were analyzed. Results : There were 67(64.4%) patients in AD group and 37(35.6%) patients in IMH group. There were 48(61.5%) and 14(31.1%) males in AD and IMH group, respectively(p<0.05). In the treatment modalities, surgical treatment was performed significantly much in AD group than in IMH group(p=0.006). In follow-up CT, the lesion size was significantly decreased in IMH group than in AD group(p<0.001). IMH group tended to be completely or partially resolved. Mortality was significantly lower in IMH group than in AD group(p=0.041). In follow-up CT, there showed no difference of interval change between surgical and medical group(p=ns). However, the lesion size of surgical group was significantly decreased than that of medical group in AD(p=0.010). There was no difference of mortality between surgical and medical group although medical group tended to be lower mortality than surgical group(p=0.064). There was no difference of mortality between surgical and medical group in every AD and IMH although medical group in AD tended to be lower mortality than surgical group in AD(p=0.073). Conclusion : Follow-up CT in IMH group showed significant regression than in AD group. Mortality was significantly lower in IMH group than in AD group. There showed no significant difference of mortality between surgical and medical group although medical group tended to be lower mortality.