Aims: Hydroxyapatite HA-coated hip replacements were introduced in the late 1980ñs when the intermediate term results of porous-coated hip replacements were not proving to be satisfactory with a high rate of thigh pain even well þxed implants. The aim of our retrospective study was to review the results of group of patients who underwent HA-coated cup between 1992 and 2001, and evaluate the clinical and radiological outcome of the HA-coated cup over a 7 to 10 year period. Methods: In a multicenter study between 1992 and 2001 were used 2899 Bihapro cups (Biomet-Merck). This is a press-þt model with a porous surface coated with hydroxyl-apatite and three peripheral þns to improve primary þxation and also dome holes to allow the use of bone screws. In 993 (34.2%) cases a posterior approach was performed, lateral approach in 1419 (49%) and the anterior approach in 487 (16.8%) cases. All patients were mobilised on the second post-operative day once drains had been removed. They were encouraged to use crutches while walking for the þrst 6 weeks. Results: 35 patients (1.2%) showed dislocation. 47% of the seires had some degree of periarticular ossiþcation one year after surgery; the approach used did not show signiþ-cative differences. The survival study was done using Kaplan-Meierñs score. The end point for failure in this study was the need to perform aseptic revision surgery; being the survival at 9 years of 99.49% (CI 95%: 99.08 Ð 99.90).Conclusions: The acetabular shells with plasma spray porous coating in combination with HA results stable at mid term. The supplementary þxation of the three peripheral þns avoids micromotion optimizing lon-term þxation.