Of seventy-three adults who were treated for osteoarthritis of the hip by medial-displacement intertrochanteric osteotomy done by one of us, sixty-one (with sixty-seven treated hips) could be evaluated twelve to fifteen years after osteotomy or at the time when they had an arthroplasty for recurrent symptoms. Specific criteria based on preoperative data were used prospectively to categorize the hips as to their suitability for medial-displacement osteotomy. In addition, at the conclusion of the study, an osteotomy suitability score (maximum score, 12 points) was assessed retrospectively as a determinant of suitability for medial-displacement osteotomy. Ten years after the osteotomy, thirty-four (51 per cent) of the sixty-seven hips had been treated with a cup arthroplasty or total hip arthroplasty. At the conclusion of the study (between twelve and fifteen years after osteotomy), forty-four (66 per cent) of the sixty-seven hips had had an arthroplasty. Among the sixteen hips that had been considered excellent candidates according to the prospective criteria, 85 per cent had not yet required hip arthroplasty five years after osteotomy and two-thirds had not had an arthroplasty ten years after surgery. Of the thirty hips with a suitability score of 7 points or more, 85 per cent had not required arthroplasty at five years and 67 per cent had not done so at ten years. The numerical scoring therefore appeared to be a more reliable determinant of suitability.