No ideal prosthetic conduit exists for femoropopliteal reconstruction. Expanded polytetrafluoroethylene (PTFE) has gained much greater popularity than the less expensive Dacron, despite disappointing long-term patency for each material. Few direct comparisons of results with the two materials have been performed. The concurrent experience of a single surgeon with femoropopliteal reconstructions of PTFE (n = 85) or knitted, nonvelour Dacron (KNVD, n = 38) was reviewed. Risk factors were comparable in the two groups. Overall patency was significantly better for KNVD than for PTFE (p = 0.0096 by log rank; p = 0.039 by Cox proportional hazards; 48% vs 27% at 5 years). Since in this series the overall performance of KNVD was significantly better than PTFE, a reassessment of the prosthetic materials used in femoropopliteal reconstruction is necessary. These results justify a prospective comparison of PTFE and KNVD.