Biocompatibility is a primary requirement for medical implants, as it determines the suitability of a material with body tissue. Material biocompatibility considerations go far beyond that of toxicity. Again and again, we find that the surface finish and the overall design of an implant are just as important for biocompatibility as the chemical composition of the implant. Essential to the development of an implant and its surface is that it has physical and chemical characteristics matched to the body tissues that are to be replaced. The implant, however, always behaves like a foreign body, as it is not a living, regenerating system.