We analysed in-vivo migration and wear over a long period of all-polyethylene acetabular cups which had not been affected by mechanical loosening. The selection criteria of regular radiological follow-up, good clinical outcome (Charnley score of 5 or 6), continued walking without crutches and no radiological signs of loosening of the acetabular cups were fulfilled by 25 Charnley total hip arthroplasties.