Adhesion, proliferation and motility of bovine pulmonary artery endothelial cells and of rat calvarial osteoblasts were examined in vitro and on glass surfaces modified with immobilized bioactive peptides. The peptides Arginine-Glycine-Aspartic Acid-Serine (RGDS), Arginine-Aspartic Acid-Glycine-Serine (RDGS), and Tyrosine-Isoleucine-Glycine-Serine-Arginine-Glycine (YIGSRG) were covalently bound to aminophase glass. The results of this study showed that modification of the substrate surface with immobilized peptides affected each cell line in different ways. Incorporation of this knowledge in the design of implant materials could result in biomaterials which promote and/or sustain a number of desirable cellular functions at the tissue-implant interface.