We report a case of aortic wall rupture in a patient with a Medtronic Freestyle stentless bioprosthesis (Medtronic Inc, Minneapolis, MN) after full root implantation. A 68-year-old man who underwent aortic root replacement with a Freestyle bioprosthesis 12 years prior was found to have a large pseudoaneurysm originating from the ruptured noncoronary porcine aortic sinus. A reoperation for aortic root replacement was successfully performed. Despite excellent durability of porcine aortic root bioprostheses, several cases with a ruptured aortic wall have been reported. Degeneration of the elastic tissue and inflammatory reactions may be the main mechanism of this potentially catastrophic complication.