Sixty-seven cases of total arthroplasty of the hip in the presence of sepsis performed between 1974 and 1986 were reviewed. These prostheses were inserted in 57 cases to replace septic prostheses. Forty-six were infected total hip prostheses and 11 were infected head and neck replacement femoral prostheses. In 10 cases arthroplasty was performed for subacute septic arthritis, usually secondary to trauma. In seven cases, a simple revision of the prosthesis by excision and lavage of infected tissues was performed. In 51 cases, a total hip replacement arthroplasty was performed in one stage. When one of the components was not loose it was preserved; in 17 cases the femoral cement was retained and in six the acetabular cup was retained. In eight cases, the prosthesis was removed, excision of the tissues was made and a total hip arthroplasty inserted after a minimum interval of six months. As regards infection, success was achieved in 69 per cent of cases rising to 85 per cent after secondary removal of the prosthesis. In relation to function, a good or fair result was achieved in 72 per cent of cases. The results were favourable in 81 per cent of cases with complete exchange of prostheses and in 75 per cent with preservation of the femoral cement. Preservation of the acetabular cup was only successful in 40 per cent of cases. Accessory factors in the prognosis were the addition of a bone graft, which became incorporated in 29 cases out of 30 and the nature of the organism which was of no significance, except that staphylococcus epidermidis and Koch's bacillus proved to be more easy to treat.