Background-Repair of a dissected aorta involves reattaching the media with synthetic glue and/or reinforcement with nonbiodegradable felt. Late complications specific to each aspect of this procedure have been reported. We attempted to regenerate the media by using biodegradable felt. Methods and Results-We created a canine model of descending thoracic aortic dissection and compared 4 modes of aortic repair: biodegradable polyglycolic acid (PGA) felt in the media; PGA with basic fibroblast growth factor (bFGF) in the media; PGA with bFGF in the media plus external reinforcement with expanded polytetrafluoroethylene; and primary suture closure of the dissected lumen (control). Repaired aortic stumps were quantitatively tested for suture pull-out strength. Failure force improved 4-fold in all 3 medial reinforcement groups compared with controls. Additionally, animals were kept alive for histological examination and compliance testing 6 months after repair. Compliance of the aortic wall at the anastomotic sites was not essentially affected in the long term except in the group with concomitant external reinforcement (55.9±4.5% reduction; P<0.05). In this group, elastic fiber in the media and collagen fiber in the adventitia tended to diminish relative to the other groups. Regarding vessel density in the repaired false lumen, this external reinforced group had a significantly decreased number. Histological derangement was not observed in control or medial reinforcement groups. Basic FGF, applied with PGA in the dissected lumen, failed to yield additional modifications in this model. Conclusions-Medial reinforcement provides sufficient augmented strength for aortic surgical repair. Medial regeneration using biodegradable felt as a scaffold preserves histological integrity and compliance in the canine dissected aorta.