: The efficiency of the M. E. Muller acetabular roof reinforcement ring is documented on 141 patients with 150 operated hips since 1976 with a minimal clinically and radiologically follow-up of 6 years. The metal backing of the cup prevented cranial migration and protrusion almost completely. After 1982, when a bone bank with frozen femoral heads was established, the loss of bone stock was replaced with allograft, which can be fixed sufficiently with the reinforcement ring. In revision arthroplasty with bone stock of poor quality and quantity the acetabular roof reinforcement ring is a good method to reconstruct the acetabulum.