A non-anastomotic false aneurysm occurred in a 77-year-old male 11 years after bypass grafting between the left external iliac artery and the right femoral artery using a Cooley double velour knitted Dacron graft. The false aneurysm was caused by rupture of an artificial graft. A partial resection of the graft and its replacement using a Hemashield® graft were successfully performed. It was speculated that the mechanical stress by the inguinal band degenerated graft fibers and developed aneurysmal formation.