PURPOSE To compare midterm outcomes of optimal medical treatment (OMT) alone with OMT and thoracic endovascular aortic repair (TEVAR) of acute type B intramural hematoma (IMHB). MATERIALS AND METHODS Retrospective analysis was performed of 65 patients treated with OMT alone (31 patients) or OMT with TEVAR (34 patients) for acute uncomplicated or complicated IMHB from January 2006 to December 2015 in a single institution. Primary outcome was aortic-related mortality during follow-up. Secondary outcomes were aortic-related adverse events, all-cause mortality, and occurrence of complete aortic remodeling. RESULTS Except for the morphologic nature of the aortic lesion, no significant differences in baseline characteristics between the 2 groups were observed. Mean follow-up time was 32 months ± 19 (range, 1-120 months). Patients in the OMT group had a significantly increased rate of aortic-related mortality (12.9% vs 0% in TEVAR group, P = .046) and aortic-related adverse events (29.0% vs 0% in TEVAR group, P < .001) and an insignificant but higher trending all-cause mortality rate (38.8% vs 19.8% in TEVAR group, P = .15). The occurrence of complete aortic remodeling was significantly lower in the OMT group (15.4% vs 82.1% in TEVAR group, P < .001). CONCLUSIONS TEVAR is likely to protect from progression of IMHB and to be associated with a better prognosis than OMT alone.