Purpose: Predictors of outcome after femoroacetabular impingement (FAI) surgery are not well-documented. This study presents data from the Danish Hip Arthroscopy Registry (DHAR) for such analyses. The purpose of this study was to identify predictors of poor outcome after FAI surgery in a Danish FAI population. The primary hypothesis was that older patients, patients with severe cartilage damage and female patients might have inferior outcome results compared with younger patients, patients with minor cartilage damage and male patients. Methods: Radiological and surgical data as well as patient-reported outcome measures (PROM) from FAI patients in DHAR between January 2012 and May 2015 were collected. PROMs consisting of Copenhagen Hip and Groin Outcome Score (HAGOS), quality of life (EQ-5D), Hip Sports Activity Scale (HSAS) and Numeric Rating Scale (NRS) pain scores were assessed. The patients were divided into three age groups (< 25, 25–39 and ≥ 40 years). Cartilage injuries were classified according to International Cartilage Repair Society (ICRS) (femoral side) and modified Becks (acetabular side) classifications. A non-parametric statistic method was used to analyze the differences between the preoperative and postoperative PROM values. Results: Data from 2054 FAI procedures in DHAR was collected. 53% of the procedures were done in female patients. All HAGOS sub-scales, EQ-5D, HSAS and NRS pain (rest and walk) demonstrated significant improvements in all age groups at follow-up. Comparison between age groups demonstrated poorer outcomes in both older age groups when compared with the < 25 years age group at 1- and 2-year follow-ups. Higher degrees of femoral and acetabular cartilage injury did have a negative influence on outcome at follow-up. Comparison between genders demonstrated lower preoperative outcomes in females and lower outcome score (HSAS) 1 and 2 years after FAI surgery. Conclusions: Age above 25 and major cartilage injury might negatively affect the outcome of surgery, however, gender could not be identified as a negative predictor of clinical outcome after FAI surgery, but might negatively affect sports participation in females. Level of evidence: III, prospective cohort study.