Aortic intramural hematma(IMH) has been known as a variant of acute aortic dissection without intimal rupture. The clinical presentation mimics that of acute aortic dissection. IMH may progress to frank aortic dissection or aortic rupture. Therefore IMH maybe regarded as early sign of developing classic aortic dissection or a precipitating facter. there are Important two questions, The first is whether IMH truly represent a different pathology or simphy the precursor of the conventtional aortic dissection. The second is what the optimal mode of management of IMH is. In this study, To answer these questions, We retrospectively performed this study. Fifteen patients of IMH were included. We could follow 12 patients. Among them extention of IMH to type III aortic dissection has been observed in 2 cases(1 type A and 1 type B). One patients of type A underwent aortic graft stent deployment successfully. In the other patient of type B, who had a history of myocardial infarction and longstanding heart failure by that time, dissection developed at abdominal aorta with renal arterial involvement. The patient died of multiorgan failure despite intensive conservative managements. The remaining ten patients are alive with only medical care and with good clinical outcome. In conclusion we feel that conservative treatment of patients with IMH result in favorable outcome relatively even in the cases involving the ascending aorta. But more longterm follow-up of larger number of patients will provide better guidelines regarding the proper management of IMH.