This study addresses endothelial cell adhesion and spreading on a family of artificial extracellular matrix (aECM) proteins designed for application in small-diameter vascular grafts. The aECM proteins contain domains derived from elastin and from fibronectin. aECM I contains the RGD sequence from the tenth type III domain of fibronectin; aECM 3 contains the fibronectin CS5 cell-binding domain. Negative control proteins aECM 2 and 4 are scrambled versions of aECM I and 3, respectively. Competitive peptide inhibition studies and comparisons of positive and negative control proteins confirm that adhesion of HUVECs to aECM proteins I and 3 is sequence specific. When subjected to a normal detachment force of 780 pN, 3-fold more HUVECs remained adherent to aECM I than to aECM 3. HUVECs also spread more rapidly on aECM I than on aECM 3. These results (i) indicate that cellular responses to aECM proteins can be modulated through choice of cell-binding domain and (ii) recommend the RGD sequence for applications that require rapid endothelial cell spreading and matrix adhesion.