Untreated femoro-acetabular impingement is a common cause of osteoarthrosis of the hip. Surgical debridement of the adult hip with femoro-acetabular impingement recently has been advocated with the aim of relieving symptoms and slowing or halting progression of the arthrosis. At surgery, femoral sources of impingement are relieved by debriding the aspheric peripheral portion of the femoral head and the adjacent femoral neck. Acetabular sources of impingement can be relieved by debridement of the anterior rim. The most fundamental questions concerning these procedures relate to the preoperative and postoperative function, postoperative survivorship of these hips and the incidence of osteonecrosis. The current study assesses a group of 23 hips in 23 patients treated by surgical debridement for impingement. Twenty-two patients were treated by full surgical dislocation and one patient was treated by relief of impingement without dislocation. Followup ranged from a minimum of 2 years to 12 years. At most recent evaluation, seven patients had been converted to total hip arthroplasty, one had arthroscopic debridement of a recurrent labral tear, and 15 patients have had no further surgery. No hips developed osteonecrosis. Of the seven patients who had to have their procedure converted to total hip arthroplasty, three of these hips failed early and four patients' hips recovered and functioned well and subsequently deteriorated with total hip arthroplasty done between 6.4 and 9.5 years after debridement. Hips at greatest risk of failure have advanced arthrosis or a combination of impingement and instability preoperatively. The procedure effectively treats hips with impingement and without considerable secondary arthrosis or instability.