Although carotid patch angioplasty has been performed on a selective or routine basis in all large series of carotid endarterectomy, the choice of patch material still remains in question. The objective of this study has been a prospective randomized evaluation of the relative risks and benefits of saphenous vein patch versus PTFE patch material for carotid endarterectomy. During a 4-year period, 84 patients undergoing 95 carotid endarterectomies were randomized into two groups: 45 venous patch (n = 40) and 50 PTFE patch (n = 44). All operations were carried out under general anesthesia and systematic placement of a shunt. The patients were evaluated at 1, 3, 6 months and every year with doppler, periorbitary photoplethysmography, intravenous digital subtraction angiography, and neurologic assessment (mean follow-up 29 +/- 1 month). Operative time among patients having PTFE patch was significantly longer (p < 0.05) than among those having saphenous vein patch, due to bleeding from suture holes. Perioperatively, no neurologic complications or deaths were observed in venous patch patients, however there was a permanent stroke and one death from arterial wall disruption in the PTFE patch group. The incidence of aneurysmal dilatation in the saphenous vein patch group (15.5%) was higher than for the PTFE patch group (2%). On late follow-up, no deaths, carotid thrombosis or patch rupture were observed in either group. Recurrent stenosis occurred in 2 cases having PTFE patch. One reoperation for recurrence was required. In addition, one patient with PTFE patch angioplasty developed an infected false aneurysm at 7 months.(ABSTRACT TRUNCATED AT 250 WORDS)