BACKGROUND: Hip resurfacing has been proposed as an alternative to total hip replacement in patients who have proximal femoral deformities or retained hardware in the proximal aspect of the femur. In these situations, placement of a conventional stemmed hip prosthesis would be difficult or impossible, possibly necessitating a complex osteotomy or a custom prosthesis. The purpose of this study was to evaluate a series of patients who had extra-articular deformities of the proximal aspect of the femur and/or retained hardware and who were managed with a resurfacing hip prosthesis. METHODS: Fifteen patients (seventeen hips) who underwent metal-on-metal resurfacing hip replacements were studied. Ten patients (twelve hips) had bowing or other deformities of the femur secondary to trauma, multiple epiphyseal dysplasia, renal osteodystrophy, or proximal femoral focal deficiency. Five patients (five hips) had retained hardware. Twelve of the patients (thirteen hips) had previously been told by orthopaedic surgeons that, due to the deformity or retained hardware, they could not undergo conventional total hip arthroplasty without also undergoing ancillary surgical procedures. We evaluated perioperative factors (operative time and estimated blood loss), Harris hip scores, complications, and failure rates. RESULTS: At a mean follow-up time of three years (range, two to five years), fourteen patients (sixteen hips) were doing well clinically and radiographically. Assessment of the intraoperative records revealed minimal difficulty, with a mean operative time of 104 minutes and a mean blood loss of 621 mL. The mean Harris hip score was 92 points. One patient, a fifty-nine-year-old woman, underwent two subsequent revisions-one for the treatment of a femoral neck fracture, and one for the treatment of acetabular component loosening. CONCLUSIONS: Resurfacing hip arthroplasty offers an option for patients when placement of a conventional total hip prosthesis is difficult or impossible because of the presence of proximal femoral deformities or retained hardware in or on the proximal aspect of the femur.