To date no prosthetic vascular prosthesis performs as well as autologous conduits for small diameter arterial reconstruction. We report the outcome of our first case using a new vascular prosthesis marketed by Cryolife, the SynerGraft. This Xenograft prostheses is claimed to eliminate the problems of the previous generation of gluteraldehyde treated grafts. Two 50 cm SynnerGrafts were anastomosed end to end and used as a femoral-posterior tibial bypass graft in a 68-year-old man who presented with an acutely ischaemic left leg. Our patient represented at 8 weeks with aneurysmal degeneration along the course of the graft. We urge caution in the use of these grafts until convincing data in humans is presented.