INTRODUCTION: Femoroacetabular impingement (FAI) is a frequent cause of inguinal pain. Treatment failure rates range between 2.9% and 13.2%. The aim of the present study was to assess the impact of preoperative bone deformities (BD), labral lesions (LL) and cartilage lesions (CL) on clinical results of arthroscopic treatment of FAI. MATERIAL AND METHOD: A prospective operational study included patients undergoing hip arthroscopy for FAI. All patients had full radiographic work-up and clinical assessment on Non-Arthritic Hip Score (NAHS), preoperatively and at 1year. Hips with Tönnis grade\textgreater1, coxa profunda [VCE (vertical center edge angle)\textgreater35°] or borderline dysplasia (VCE\textless25°) were excluded. The Czerny classification was used for the labrum and the Beck classification for the cartilage. The aim of the study was to assess the impact of preoperative BD, LL and CL on clinical results of arthroscopic treatment of FAI. The study hypothesis was that type of lesion does not influence early functional results at 1year, whatever the technique used for the labrum. RESULTS: One hundred and ninety-seven patients were included. Mean preoperative NAHS was 59.1±17.5. There were 145 patients with labral suture (73.6%), 42 with labral debridement (21.3%) and 10 with conservative treatment (5.1%). At 1year, mean NAHS was 88.1±15.3: i.e., a significant improvement (p\textless2.2×10(-16)). Improvement was also significant in the debridement, non-operative and suture subgroups. BD showed significant correction in the overall population (alpha angle 48.2° postoperatively versus 66.7° preoperatively; crossing sign in 14.5% versus 62.9% of cases). There were no significant differences in functional scores according to extension or type of labral or cartilage lesion. At follow-up, 3 patients (1.5%) required repeat arthroscopy. CONCLUSION: The present study showed that early functional results of arthroscopic treatment of FAI were unaffected by the severity of bone deformity (alpha and VCE angles), or extension or type of labral or cartilage lesion. Regardless of BD, LL and CL, 1-year clinical progression was satisfactory when all bone deformities were treated by the arthroscopic procedure. LEVEL OF EVIDENCE: IV; prospective non-comparative study.