A cemented Charnley total hip prosthesis was implanted in a 48-year-old man with mild haemophilia (factor VIII 4 IU dL-1) in his right spontaneously ankylosed hip. At the time of surgery he was anti-HCV positive, anti-HIV negative, and no circulating inhibitors were encountered. The indication for surgery was long-lasting intractable low back and ipsilateral knee pain. At 4-month follow-up, relief of pain was achieved as well as correction of limb-length discrepancy, with a good result according to the Mayo Clinic hip score. Doses of 50 IU kg-1 body weight of recombinant factor VIII (Recombinate; Baxter, Glendale, California, USA) was used during the 2 weeks of admittance to the hospital. The dosage was adjusted according to the recoveries of factor VIII, with an overall factor consumption of 68 000 IU. As far as we know this is the first case reported in the literature of a person with haemophilia in whom a spontaneous hip ankylosis has been satisfactorily converted in a total hip arthroplasty with a short-term follow-up. However, a much longer follow-up is still needed to ascertain the efficacy of this surgical procedure in haemophilia.