One hundred and eighty-four patients who had been managed, between 1984 and 1985, with a total of 204 consecutive primary total hip arthroplasties with insertion of a Harris-Galante type-I acetabular component without cement were prospectively studied. There were eighty-two men (45 per cent) and 102 women (55 per cent). The mean age at the time of the operation was fifty-two years (range, twenty to eighty-four years). One hundred and fifty-seven patients (173 hips) were available for clinical review at a mean of 104 months (range, seventy-eight to 126 months). At this time, the mean preoperative Harris hip score of 52 points (range, 12 to 79 points) had improved to a mean of 90 points (range, 44 to 100 points). Two patients (two hips) had had an exchange of an excessively worn polyethylene liner. One patient (one hip) had had débridement and grafting of an area of massive retroacetabular osteolysis. Two stable acetabular components (1 per cent) had been revised at the time of femoral revision. None of the cups had been revised because of aseptic loosening.Radiographic examination of 150 patients (165 hips) at a mean of 104 months (range, seventy-eight to 126 months) revealed that 156 cups (95 per cent) were stable. Eight cups (5 per cent) were considered to be possibly unstable, with a radiolucent line between the prosthesis and the bone that was one millimeter wide or less in at least four of five zones; two of the eight had a complete radiolucent line in all zones. One component, which had been implanted with a bulk allograft from a femoral head, migrated more than two millimeters in the first two years and then stabilized without complication. Osteolysis was seen in seven acetabula (4 per cent) and was limited to the periphery of the cup in six. Survivorship analysis at ten years revealed that the acetabular component had a 99 per cent chance of survival (95 per cent confidence interval, 0.98 to 1.0) with revision or aseptic loosening as the end point and a 97 per cent chance of survival (95 per cent confidence interval, 0.95 to 1.0) with revision, aseptic loosening, or reoperation because of a problem related to the acetabular component as the end point.