The authors present the long-term results of 36 SEM cemented bipolar hip prostheses for femoral neck fractures with a mean observation time of 7.4 years. The objective was to study the acetabular tolerance of these prostheses comparing with Moore's and Thompson's conventional hemiarthroplasties. The average age of the patients was of 69 years. According to the Merle d'Aubigné's classification, clinical results were better than those results reported in the literature with conventional hemiarthroplasties. At long term, acetabular deteriorations were nevertheless frequent (41.6 per cent pinchings and 25 per cent protrusions), but with no clinical significative correlation. They seem to be favoured by technical errors (drilling, size of the cups) and acetabular morphology. The part of the intermediary joint's mobility is difficult to demonstrate and is far being univocal. The authors conclude, to the superiority of the bipolar hip prosthesis actually totalizable (long term clinical results and middle term acetabular tolerance) in comparison with the conventional hemiarthroplasties, and recommend the use of those implants in sub-capital displaced femoral neck fractures for elderly patients with no arthrosis.