Abstract A new, compliant, highly porous, non-woven, polyurethane vascular prosthesis has been developed in an effort to improve on the performance of currently available prosthetic grafts for infrainguinal reconstruction. From April 1990 to August 1991, 57 femoropopliteal bypass grafts were implanted in 47 patients by surgeons at five university centres. In all instances, the saphenous vein was unavailable, unusable or reserved for use elsewhere. An empirical perioperative risk score for acute occlusion (0–20) was developed, based on such factors as severity of clinical ischaemia, quality of inflow and outflow, site of distal anastomosis and associated drug therapy. Primary cumulative patency was calculated according to standard life-table analysis. Poor inflow and a distal anastomosis below the knee were significant factors affecting graft patency ( P = 0.001 and P= 0.001 respectively). Six-month cumulative patency for the 25 grafts with good inflow and above or mid-knee anastomoses (79%) was superior to the cumulative patency for all 57 grafts (59%). There was a significant improvement in patency rates between ‘low’ (22 grafts) and 'medium risk' (27 grafts) patients and ‘high risk’ (eight grafts) ones (risk scores 0–10 and 11–20 respectively) at a level of P = 0.001. There were two operative deaths (4%). Of the 19 postoperative occlusions, six occurred within 30 days and 18 within 6 months. These data indicate that the patency rates achieved with this new graft compare favourably with other available prosthetic grafts. In addition, the graft demonstrates superior handling characteristics and eliminates bleeding through suture holes. There is also the possibility that rapid tissue ingrowth, neointima formation and compliance will reduce intimal hyperplasia and increase long-term patency.