Von Willebrand protein is present in the extracellular matrix of endothelial cells where it codistributes with fibronectin and types IV and V collagen. Bacterial collagenase digestion of endothelial cells removed fibrillar collagen, but the pattern of fibronectin and of von Willebrand protein remained undisturbed. Exogenous von Willebrand protein bound to matrices of different cells, whether rich or poor in collagen. von Willebrand protein also decorated the matrix of cells grown in the presence of alpha, alpha'-dipyridyl, a collagen-secretion inhibitor. These results indicate that the presence of von Willebrand protein in the extracellular matrix of endothelial cells and the binding of von Willebrand protein to foreign matrices do not depend on the matrix collagen.