The ICLH (Imperial College-London Hospital) total hip arthroplasty is a procedure in which a metal femoral component caps the proximal femur and a polyethylene acetabular component resurfaces the acetabulum with both components cemented in place. Between June, 1972, and November, 1974, changes were made in prosthetic design and in operative technique in response to 2 specific problems encountered. The loosening rate was high until the original polyethylene femoral component was redesigned so that it was metal. The incidence of femoral neck fractures was unacceptable until trochanteric osteotomy was discontinued. Since November, 1974, 116 hips have been replaced and neither the prosthesis nor the operative technique has changed. Pain relief has been comparable to that obtained with conventional Charnley-type hip replacement. All patients walk out of doors and no patient's walking capacity is limited by pain in the operated hip. No hip has lost motion and 36% have an effectively full range. No deterioration in the quality of these results is suggested when the first postoperative assessment is compared to those at 2 years and longer postoperative. Technical errors to be recognized and avoided are varus placement of the femoral component and excessive vertical placement of the acetabular component.