The replacement of autologous blood vessels by artificial grafts is urgently needed in clinical applications. Expanded polytetrafluoroethylene (ePTFE) grafts are the most clinically used artificial blood vessels because of its chemical and mechanical stability. But, when used as arteriovenous (AV) grafts for haemodialysis, small diameter ePTFE grafts have a high failure rate of 40% in three years in vivo because of the functional lack of an intact endothelial cell layer. Here we developed a two-step modification including chemical etching and plasma activation to enhance the hydrophilicity of ePTFE. Peptide motifs (eg. cyclic RRE, RGD) known to bind integrins on the endothelial cells were immobilized on ePTFE grafts. Functional peptide immobilization significantly increased the adherence and growth of HUVEC cells on ePTFEs. Patch ePTFE implantation in the pig's descending aorta was used to evaluate the in vivo endothelialization of these modified ePTFE grafts. At 28 days implantation, newly formed endothelial layers on peptide-immobilized ePTFE grafts were demonstrated by SEM and histological analysis. These preliminary data showed the potential to grow an intact endothelial layer to improve the patency rate of the modified ePTFE grafts.