The creation of nonthrombogenic synthetic surfaces is a major challenge in biomedical research. The feature that clearly distinguishes natural blood vessels from their artificial counterparts is the presence of endothelial cell lining that besides being nonthrombogenic is capable of repair and renewal. This study describes a method of coating vascular grafts with a uniform, naturally produced subendothelial extracellular matrix before implantation. This substrate provides a most suitable bilayer for endothelial cell adhesion, growth, and differentiation, as compared with grafts coated with fibronectin or basement membrane extracts. It contains both adhesive glycoproteins (fibronectin, laminin, collagen) and proteoglycans (heparan sulfate) as well as endothelial cell growth factors (basic fibroblast growth factor) that support adhesion and normal growth of suboptimal concentrations of endothelial cells. We suggest that the presence in extracellular matrix of both adhesive macromolecules and potent endothelial cell-growth promoting factors will make the extracellular matrix a promising substrate for vascular grafts.