Genetic engineering methods were used for the preparation of artificial proteins containing sequences designed to reproduce essential features of the extracellular matrix (ECM). The long-term objective of the work is to develop matrices for use in the engineering of small-diameter vascular grafts. The CS5 domain of fibronectin provides binding sites for vascular endothelial cells, while an elastin-like repeat, [(VPGIG)(2)(VPGKG)(VPGIG)(2)], controls the mechanical properties and includes sites for covalent cross-linking. Bis(sulfosuccinimidyl) suberate and disuccinimidyl suberate were used to cross-link artificial ECM protein films for uniaxial tensile testing. Variation in the amount of cross-linker and protein weight fraction allowed preparation of films with Young's moduli ranging from 0.07 to 0.97 MPa. The weight fraction of protein in the hydrated, cross-linked films was measured to be between 0.2 and 0.4; the molecular weight between cross-links (M-c) varied from 3000 to 38 000. The moduli and M, of the films span the ranges reported for natural elastins.