Background and Objectives: The aim of this study was to compare the characteristics and outcomes between aortic dissection (AD) and intramural hematoma (IMH) in a single tertiary center for recent 5 years. Methods: A total of 256 patients were divided into 2 groups; AD group (n=197, 108 males, 57.7짹14.2 years) vs IMH group (n=59, 21 males, 65.1짹10.8 years). The patients who had both AD and IMH (n=52) simultaneously were classified into AD group in the present study. Results: AD group was younger than in IMH group (57.7짹14.2 vs 65.1 10.8 years, p<0.001). AD was more common in males than IMH (54.8% vs 35.6%, p=0.01). Other clinical, laboratory, electrocardiographic, or echocardiographic findings were not different between the groups. Stanford classification (type A or B) was also not different between the groups. Fifty four patients were died during hospitalization and clinical follow-up (21.1%), and the mortality rate was not different between the groups (22.4% vs 16.9%, p=ns). The dead patients were significantly older than in the survived patients in both groups (62.6짹13.5 vs 56.3짹14.1 years, p=0.008 in AD group, 73.6짹10.0 vs 63.4짹10.2 years, p=0.006 in IMH group). Type A involvement by Stanford classification was a significant predictor of mortality in AD group (mortality: 28.9% in type A vs 13.3% in type B, p=0.009), but no in IMH group (mortality: 20.7% in type A vs 13.3% in type B, p=0.451). Conclusion: The present study suggested that IMH develop more commonly in female and older age than AD and the type of acute aortic syndrome whether it was AD or IMH was not a predictor of mortality. Age was a significant predictor of mortality in both AD and IMH, but the Stanford classification was more important predictor of mortality in AD.