Experiments were performed in a wear machine especially constructed to simulate the natural in vivo process of wear in a de-bonded metal-cement interface. Four different bone cements were fretted against S-30 stainless steel with mat surface finish. The validation of the metal surfaces of the in vitro experiments revealed excellent correspondence to examined retrieved hip stems. No scratches or fretting orientation was noted on the polished surfaces. ZrO₂ particles did not play a decisive role in the wear mechanism. PMMA as a softer material than S-30 steel did not mechanically abrade the metallic surface. Further no steel particles could be found within the wear debris. Metal is removed by dissolution in a process of fretting and crevice corrosion. Fretting corrosion causes the formation of debris in the form of a mixture of particles of metallic oxides (but not metallic particles!), polymer and serum.