Background: The aim of the present study was to evaluate in-hospital and long-term clinical outcomes in patients with aortic dissection (AD) and intramural hematoma (IMH). Moreover, we investigated computed tomography (CT) findings related to in-hospital, long-term clinical outcomes, and progression of lesion on CT. Methods: One-hundred twenty consecutive patients with AD (n=70) and IMH (n=50), documented by CT imaging, who visited Kyungpook National University Hospital between January 2004 and April 2009 were included in the final analysis. In-hospital clinical events included death and surgery during admission. Long-term clinical events included death and readmission, surgery, and pain due to AD or IMH. We analyzed CT findings with regard to the following: involved site, branch vessel involvement, maximal thickness of aorta, false lumen, and hematoma, pericardial and pleural effusion, and longitudinal length of involved aorta. Mean follow-up duration was 752짹584 days. Results: AD group received more surgery (63% vs. 40%, p=0.013) and had a tendency of higher mortality during admission (7% vs. 2%, p=0.339) compared with IMH group. Among AD group, long and short axis of aorta (52 mm vs. 48 mm, p=0.034; 48 mm vs. 44 mm, p=0.034, respectively), long and short axis of false lumen (45mm vs. 39mm, p=0.050; 30mm vs. 21 mm, p=0.037, respectively), and longitudinal length of involved aorta (465mm vs. 291mm, p=0.001) were longer, renal artery involvement (100% vs. 43%, p=0.020) and pleural effusion (80% vs. 19%, p=0.008) were more frequent in patients with in-hospital death. There was a tendency of more long-term clinical events (23% vs. 10%, p=0.074) in AD group compared with IMH group. Among AD group, Stanford type B (73% vs. 36%, p=0.011) was more frequent and long axis of false lumen (41 mm vs. 33mm, p=0.017) was longer in patients with long-term clinical events. AD group had more progression of lesion (37% vs. 19%, p=0.041) compared with IMH group. Among AD group, Stanford type B (68% vs. 35%, p=0.014) was more frequent and involved site (3.1 vs. 4.7, p=0.002) and branch vessel involvement (1.1 vs. 2.2, p=0.012) were less frequent, and longitudinal length of involved aorta (251 mm vs. 340 mm, p=0.015) was shorter in patients with progression of lesion. However, there were no significant variables regarding in-hospital, long-term clinical outcomes, and progression of lesion in IMH group. Conclusions: Compared with IMH, patients with AD had more frequent in-hospital and long-term clinical events as well as more progression of lesion on CT. Long axis of false lumen was a useful parameter related to in-hospital and long-term clinical outcomes.