Radiological assessment revealed a complete osseoin-tegration in all 3 zones according to DeLee and Charnley in 98%. 1 cup with a continuous radiolucent line implanted after a acetabulum fracture had to be revised after a 13 year follow-up. 10 cups migrated either in the vertical or horizontal plane 2–5 mm without any progression after 2 years postoperatively. One cup had expansile osteolyses and had therefore to be revised after 13 years. With this exception there was no evidence of osteolyses in the periacetabular pelvic bone. Brooker III and IV ectopic ossifications was seen in decentration of the head of the stem as a sign of increased polyethylene-wear. Discussion: The excellent clinical and radiological results are supported by histologic investigations of 27 autopsy-specimens which show throughout a perfect osseoin-tegration with reinforcement of the osseous anchoring in the peripheral zones of the press-fit cup. We explain the wide absence of osteolyses with the disclaiming of a metal backing (preservation of elasticity and avoiding of stress shielding) and the disclaiming of using screws.