PURPOSE: The timing of psychological and physical recovery after anterior cruciate ligament reconstruction represents an open issue in current orthopedic practice. Several tools have been developed to evaluate these factors, with the most recent being represented by the anterior cruciate ligament (ACL) return to sport injury scale (ACL-RSI). The aims of this study were to provide a validated Italian translation of the ACL-RSI in a population of sport patients, and to identify a possible correlation of the ACL-RSI score with the return to sport (RTS) time and the level of sport participation in comparison to the pre-injury one. METHODS: The Italian translation and cultural adaptation of the scale were completed using a using the "translation-back translation" method. A total of 130 patients were enrolled and completed the study questionnaires 6 months after ACL reconstruction. Randomly, 65 of them were re-tested for the ACL-RSI within 2 weeks. The internal consistency, reliability, feasibility, and construct validity of the Italian version of ACL-RSI were assessed and compared to Italian version of the KOOS, the Lysholm Score, the AKPS and the IKDC subjective score. Responsiveness was tested comparing patients returning to sport at 6 and 12 months. The Tegner activity scale was collected at baseline, 6 and 12 months to identify the level of activity after return to sport, in relation to the ACL-RSI score. RESULTS: The Italian adaptation of the ACL-RSI demonstrated excellent internal consistency (Cronbach's alpha = 0.953), reliability (test-retest ICC = 0.916) and feasibility, with no ceiling or floor effect. Construct validity was confirmed by the moderate to strong correlation with all the other scales (p < 0.0001). Slight and non-significant higher ACL-RSI score was shown by patients returned to sport at 6 or 12 months after surgery. Nevertheless, the ACL-RSI score at 6 months was significantly different between patients who returned and those who did not returned to the same level of sport activity 12 months after the procedure. CONCLUSIONS: This study demonstrated that the Italian ACL-RSI is a reliable tool for evaluating the psychological readiness for return to sports of athletes who underwent ACL reconstruction, especially when collected at the end of the rehabilitation process. Since the IT ACL-RSI used in this study is a faithful translation of the original English version, this finding can be generalized to other cultural contexts and languages too. LEVEL OF EVIDENCE: Level II.