Sixty-six patients were revised for aseptic loosening of their conventional hip arthroplasties; follow-up periods ranged from one to nine years. In comparing them with an overall conventional arthroplasty series, there was a higher failure rate with dysplasia and post-traumatic patients, and a lower incidence in osteoarthritic and rheumatoid patients. The average time to revision was four years. The patients were eight years younger than those in the overall UCLA conventional hip arthroplasty series. Forty-two per cent had undergone hip surgery prior to the original hip arthroplasty that failed. The average improvement, as well as the follow-up pain, walking, and function ratings, and the postoperative flexion arc were less than those in the overall conventional arthroplasty series. The quality of femoral and acetabular fixation obtained at revision was considerably inferior to that of the primary surgery. Six patients (9%) have already required re-revision of their hip arthroplasties. In a further 20%, the radiolucencies progressed substantially in extent and width, and are radiographically loose. Although these patients are relatively asymptomatic, prognosis is guarded. Forty-four per cent had no complications and are radiographically well fixed. Other complications included trochanteric migration (7.6%), dislocation (10.6%), and peroneal nerve palsy (7.6%), but there were no deaths or other serious medical complications and only one case (1.5%) of sepsis.