AbstractBiomaterials are materials that are used in medical devices that are intended to interact with biological systems. These medical devices include the now common hip replacements and prosthetic heart valves, and the less common neurological prostheses and implantable drug delivery systems. Biomaterials include the traditional stainless steel, titanium, polyethylene, and polymethyl methacrylate and the more biologically sophisticated calcium hydroxyapatite, surface modified polymers, and glass ceramics. In this paper, some of the principles that are involved in the selection and use of these materials in present and future medical devices are discussed.MST/663