Between 1970 and 1982, sixty-six total hip replacements were performed with cement, without bone-grafting, in fifty-three patients who had congenital dysplasia and dislocation of the hip. Preoperatively, the patients had had Crowe type-II, III, or IV subluxation. Current information was available for fifty-nine hips in forty-six patients after an average duration of follow-up of sixteen years (range, ten to twenty-one years). The average age of the patients at the time of the operation was fifty-three years (range, twenty-three to seventy-three years). The average Harris hip score at the most recent examination was 92 points (range, 61 to 100 points). Eight hips were revised. The reason for the revision was infection in two hips, fracture of the femoral stem in two, and loosening of the acetabular component in four. The rate of revision for aseptic loosening, therefore, was 10 per cent (six hips). In the unrevised hips for which radiographs were available, the rate of radiographic loosening of the femoral component was 5 per cent (two hips) and that of the acetabular component was 32 per cent (twelve hips). We did not find a relationship between the amount of horizontal or vertical displacement of the center of the femoral head and the rate of loosening. Kaplan-Meier survivorship analysis with revision as the end point predicted a rate of survival of 85 per cent (95 per cent confidence interval, 75 to 95 per cent) at fifteen years. With radiographic loosening as the end point, the predicted rate of survival was 68 per cent (95 per cent confidence interval, 54 to 81 per cent) at fifteen years. We concluded that, for patients who have Crowe type-II, III, or IV congenital dysplasia of the hip, good long-term results can be obtained with insertion of a femoral stem with cement. The high rate of loosening of cemented acetabular components is a concern.