Polymers have been used in the human body for the last 25 years for things such as vascular grafts, pacemaker leads and joint replacement. Until recently, these polymers have been polyesters or polyethers. The newest polymers, developed by Corvita Corporation, are polycarbonates. These polymers have shown better resistance to biodegredation than their predecessors1. These newer polyurethanes are now being used in applications, such as stent grafts, where they were not before. The new polymer structure, method of manufacture and characteristics allow the material to be used in arterial vascular graft applications.