Abstract : The surgical treatment of femoroacetabular impingement has become more common, yet the strength of clinical evidence to support this surgery is debated. We performed a systematic review of the literature to (1) define the level of evidence regarding hip impingement surgery; (2) determine whether the surgery relieves pain and improves function; (3) identify the complications; and (4) identify modifiable causes of failure (conversion to total hip arthroplasty). We searched the literature between 1950 and 2009 for all studies reporting on surgical treatment of femoroacetabular impingement. Studies with clinical outcome data and minimum two year followup were analyzed. Eleven studies met our criteria for inclusion. Nine were Level IV and two were Level III. Mean followup was 3.2 years; range (2-5.2 years). Reduced pain and improvement in hip function were reported in all studies. Conversion to THA was reported in 0% to 26% of cases. Major complications occurred in 0% to 18% of the procedures. Current evidence regarding femoroacetabular impingement surgery is primarily Level IV and suggests the various surgical techniques are associated with pain relief and improved function in 68-96% of patients over short-term followup. Long-term followup is needed to determine survivorship and impact on osteoarthritis progression and natural history. Level of Evidence: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.