Bioactive polyurethaneurea modified with polyethylene glycol (PEG) and the endothelial cell-adhesive peptide YIGSR was synthesized and fabricated into microporous scaffolds. This material has shown appropriate mechanical properties for vascular graft applications, resists platelet adhesion, and promotes endothelialization. In the current study, microporous scaffolds were formed by a gas-foaming and salt-leaching method. The scaffolds showed highly interconnected open pores throughout the matrices, with porosity of approximately 78% and pore sizes of 20-200 μm. The peptide modified scaffolds showed superior mechanical properties over peptide-free scaffolds (tensile strength, 1.4 ± 0.03 versus 0.19 ± 0.01 MPa; p < 0.01). Bovine aortic endothelial cells were seeded on the scaffolds, and cell attachment, proliferation, extracellular matrix production, and migration were investigated. Histological and scanning electron microscopy analysis showed that few cells adhered on peptide-free scaffolds, whereas confluent endothelial cell monolayers formed along the pores in peptide-modified scaffolds. DNA content, hydroxyproline production, and cell migration were also significantly greater in peptide-modified scaffolds. © Mary Ann Liebert, Inc.