The quality of the early cell/material interactions is responsible for the long-term functional properties of any implanted device. Accordingly, "next generation" dental/orthopedic biomaterials should be able to promote osteoblast adhesion thus improving the integration process between surgically placed implants and biological tissues. Recent studies have identified a wide range of biochemical signals that can be exploited to promote adhesion, migration, proliferation and differentiation of cells. The clinical use of natural factors to promote osteoblast adhesion is complicated because those are often insoluble and unstable macromolecules and, in addition, it is difficult to obtain them in high quantities, with good purity grade and at low cost. A valid alternative could be the use of short peptides carrying the minimum active sequence of the natural macromolecular factor. This paper describes the properties of two classes of peptides, promoting different adhesion mechanisms, to enhance rat bone marrow osteoblast adhesion both to polystyrene and to acellular bone matrix.