The search for an endoprosthesis with the longest possible durability has been in progress for many years. In spite of three decades of intensive development of implant materials, contemporary endoprosthesis are still far from satisfactory. In an environment as corrosive as the human body, even the best metal alloys release ions: Co, Cr and Mo all dissolve at a rate of approximately 50 ng per year. The biocompatibility of an implants is directly by the extent of corrosion. Tests in vivo have shown that Ni, Co and Cr ions are bound to the body's own proteins, predominantly albumins, which can then transfer them to other ergans, thus disturbing their functions.<br /> Facing this challenge, a new, entirely cementless endoprosthesis for the coxofemoral joint, comprised of a pin, a head and two bushings, has been constructed in a cooperative project involving three research centers: ECAM in Lyons, the Technical University of Bratislava, and the Thin Film Division of the Technical University of Lodz. Both the pin and the outer bushing are made of a titanium alloy, coated with a nanocrystalline diamond film. The heads is made of corundum ceramics, and the inner bushing is made if high molecular weight polyethylene. The shape of the pin has been designed in compliance with all biomechanical requirements.<br /> As of this writing these endoprostheses have been implanted in test animals, and remain under continous biological monitoring. To this point all the test results have been postitive.