Platelet deposition onto double velour Dacron (n = 14) and double velour Dacron with internal collagen (n = 14) interposition grafts were examined experimentally. The accumulation was assessed by reinfusion of 111In labelled platelets and imaging with a scintillation camera. One group received Dextran-40 intravenously (n = 14) and one group received Dazmegrel (n = 14) intravenously. No graft occlusions were noted. Differences in effects of Dextran-40 and Dazmegrel were not observed. The study indicates a beneficial effect of infused Dextran-40 as well as Dazmegrel. The explanation might be reduced interaction graft wall versus blood-platelets.