Implant materials are categorized in four main groups, namely metals, ceramics, polymers and composites. The use of an implant in the body depends on many factors, especially material features, design and biocompliance. The most important material feature is the maintainance of the material properties in biologic medium without deterioration. Implant materials undergo mechanical and biological degradation in two ways, namely mechanical and biological. The degradation of the implants varies according to the type, usage area and the movement of this area. It is possible to classify the mechanisms leading to the degradation of implant materials into mechanical, physicochemical, electrochemical and biochemical/ electrochemical reactions. Of these mechanisms, the frequently encountered degradation types are corrosion in metals, degradation in ceramic materials and various physicochemical reactions in polymeric materials.