To estimate the sensitivity of magnetic resonance imaging (MRI) as a diagnostic test in anterior cruciate ligament (ACL) injuries, as well as its correlation with arthroscopic findings. Methods. Retrospective analysis of 270 patients who underwent ACL reconstruction surgery in our health department between 2007 and 2017. ACL injuries were diagnosed by radiologists specialized in musculoskeletal pathology, while the correlation between radiological and arthroscopic findings was determined through statistical analysis. Results. The sensitivity of the MRI regarding diagnosis of ACL injuries was 88.5%. In addition, the correlation between radiologic and arthroscopic findings was 73.3%. In 71% of the patients with persistence of the symptoms and a negative-result MRI, the diagnostic method chosen was diagnostic-therapeutic arthroscopy. Conclusions. MRI is a non-invasive, quick and accurate test for diagnosing ACL injuries, which makes it, along with physical exam, a fundamental diagnostic test. However, diagnostic-therapeutic arthroscopy is currently the gold-standard in a patient with a negative-result MRI and a high suspicion of ACL injury.