The thrombogenicity of the graft materials is a significant factor incriminated in early failures. Some improvements have been achieved by modification of physical characteristics of the material as porosity, compliance, durability in order to improve patency rates. Platelets are major determinants of thrombus formation and may still be thrombogenic by activation of the coagulation enzymes. The purpose of this work is to study the platelets deposition on different material grafts, utilizing autologous platelets labelled with 111-Indium. The radioactivity pulses was recorder before and 4 days after surgery in aortoiliac and femoropopliteal districts. The graft material used in aortoiliac occlusions was: velour, double velour PTFE; in femoropopliteal: Double velour, PTFE, saphenous vein, umbilical vein, bovine carotid. In some patients the operation was TEA with patch in PTFE. The authors show the results of this study in 92 patients in relation of the material graft an location.