Background—Retrograde type A aortic dissection has been deemed a rare complication after endovascular stent graft placement for type B dissection. However, this life-threatening event appears to be underrecognized and is worth being investigated further. Methods and Results—Eleven of 443 patients developed retrograde type A aortic dissection during or after stent grafting for type B dissection from August 2000 to June 2007. Of these 11 patients, 3 had Marfan syndrome. The Kaplan–Meier estimate of the rate of freedom from this event at 36 months is 97.4% (95% confidence interval, 0.95 to 0.99). The new entry was located at the tip of the proximal bare spring of the stent graft in 9 patients, was within the anchoring area of the proximal bare spring in 1, and remained unknown in 1 patient. Eight patients were converted to open surgery, and 2 received medical treatment. One patient suddenly died 2 hours after the primary stent grafting, and 2 died within 1 week after the surgical conversion, so mortality reached 27.3%. During the follow-up from 3 to 50 months, type I endoleak was identified in 1 patient 3 months after the surgical exploration and disappeared at 6 months. Conclusions—Retrograde type A aortic dissection after stent grafting for type B dissection appears not to be rare and results from mixed causes. Fragility of the aortic wall and disease progression may predispose to it, whereas stent grafting–related factors make important and provocative contributions. Avoiding aortic arch stent grafting in Marfan patients, preferably selecting the endograft without the proximal bare spring for patients with a kinked aortic arch or with Marfan syndrome (if endografting is used), improving the device design, and standardizing endovascular manipulation might lessen its occurrence. (Circulation. 2009;119:735-741.)