Abstract Polymers are increasingly used in bioscientific device applications, such as dialysis units, vascular grafts, ocular contact lenses, comprehensive heart-and-lung machines, and sophisticated prosthetic devices such as hip-joints. Yet commercial polymers are in general unsatisfactory biomaterials. This is due to variability in composition, stability, surface smoothness, and the presence of impurities during production. On the other hand we have already successfully demonstrated that many of the mechanical and physical properties of polymers can be substantially improved by modifications of the surface by simple ion irradiation. Ion irradiation and track etch techniques have been used in a study of the surface properties of polymeric biomaterials, including polyetheylene, and teflon. The experimental results on surface improvement - especially wear, and stability under irradiation are discussed against the theoretical background of ion ranges and energy deposition in the polymer at the atomic/molecular level. Some new and exciting potential commercial applications are briefly referred to. There are implications for all polymeric biomaterials in this most recent practical approach to modification of basic physico-chemical properties. A high added value accompanies the much improved reliability of polymeric medical applications, and a greater compatibility with human tissue.