Objective: To describe our experience with endovascular stent-graft repairs in type B aortic dissection focusing on serious secondary complications resulting in immediate or late conversion to open repair. Methods: From November 1997 to May 2007, 28 patients underwent a thoracic endovascular stent-graft procedure for acute symptomatic type B dissection at our institution. Indication for endovascular repair at our department is a complicated course of type B dissection, including thoracic aortic rupture, suspicion of impending rupture, visceral and/or peripheral ischemia, uncontrollable hypertension, and severe therapy-resistant pain. Median follow-up time was 48.3 months (range 2–97 months). Results: Secondary complications with indication for a secondary intervention occurred in 5/28 patients, resulting in additional procedures in 4 patients. One patient declined any further therapy. Conversion to an open procedure was performed in four patients, one due to type I endoleak followed by retrograde type A dissection, and three due to retrograde type A dissection. One of these patients had an additional stent-graft procedure performed due to a type III endoleak 20 months post stent grafting. Retrograde type A dissection occurred 39 months later, finally leading to conversion to an open procedure. Open surgery was performed in four patients after 3, 26, 29, and 1170 days post stent-graft placement and was successful in three patients. The fourth patient died 3 months post-surgically due to multi-organ failure. The procedure-related mortality rate following secondary complications was (1/5) 20%. Conclusions: Endovascular stent-graft repair of the thoracic aorta is an alternative to surgical repair, however not without significant morbidity and mortality. Potentially lethal complications, acute or delayed, may occur.