Expanded polytetrafluoroethylene grafts were used in 44 patients in the last 18 months. In 13 patients the graft was used for various types of peripheral vascular reconstructive procedures, as a substitute of the autogenous saphenous veins. In 31 patients the prosthesis was used for the construction of vascular access for hemodialysis. Results of the use of this new vascular prosthesis are comparable to those achieved with the autogenous saphenous vein when used for the same purposes. A much longer period of observation is necessary before a definitive verdict can be reached on the safety and clinical applicability of any new vascular prosthetic material. But preliminary clinical results with the PTFE vascular prosthesis are encouraging and seem to justify continued cautious application of this vascular substitute.