The Swedish Hip Replacement Registry has defined the epidemiology of total hip replacement in this country. Most hip replacements are fully cemented. Serious complication and revision rates associated with total hip replacement have declined significantly despite increase in the number of patients at risk. During the past five-year period, only 8(9 per cent of hip replacement procedures have been revisions. Although aseptic loosening with or without osteolysis is the major problem, accounting for 73 per cent of revisions, its incidence has decreased four-fold over the past 15 years to less than three per cent at 10-year follow-up. Quality of the surgical technique is the crucial determinant of the risk of revision due to aseptic loosening, but the choice of implant is also important. Total hip replacement practice in Sweden has improved due to the information available from the registry concerning individual risk factors, implant safety, and the efficacy of improving surgical and cementing techniques.