Forth hips in 35 patients were converted from pseudarthrosis to low friction total hip arthroplasty (LFA). Pain, function and range of motion were improved in most cases. Gait was improved and number of walking aids required were reduced in most cases. Abduction against gravity and straight leg raising were also improved. Limb length was restored in all but 9 cases. Two cases dislocated postoperatively. One was reduced and did well; the other had a trochanter avulsion with recurrent subluxation. Improvement of function is a prime indication for converting a pseudarthrosis to LFA whereas pain is not so significant a factor. This is a formidable procedure requiring a complete range of prostheses and instruments and complete familiarity with the technique of total hip replacement but the end results are gratifying.