Background: Numerous clinical tests are used in the diagnosis of anterior cruciate ligament (ACL) injury but their accuracy is unclear. The purpose of this study is to evaluate the diagnostic accuracy of clinical tests for the diagnosis of ACL injury.Methods: Study Design: Systematic review. The review protocol was registered through PROSPERO (CRD42012002069).Electronic databases (PubMed, MEDLINE, EMBASE, CINAHL) were searched up to 19th of June 2013 to identify diagnostic studies comparing the accuracy of clinical tests for ACL injury to an acceptable reference standard (arthroscopy, arthrotomy, or MRI). Risk of bias was appraised using the QUADAS-2 checklist. Index test accuracy was evaluated using a descriptive analysis of paired likelihood ratios and displayed as forest plots. Results: A total of 285 full-text articles were assessed for eligibility, from which 14 studies were included in this review. Included studies were deemed to be clinically and statistically heterogeneous, so a meta-analysis was not performed. Nine clinical tests from the history (popping sound at time of injury, giving way, effusion, pain, ability to continue activity) and four from physical examination (anterior draw test, Lachman's test, prone Lachman's test and pivot shift test) were investigated for diagnostic accuracy. Inspection of positive and negative likelihood ratios indicated that none of the individual tests provide useful diagnostic information in a clinical setting. Most studies were at risk of bias and reported imprecise estimates of diagnostic accuracy.Conclusion: Despite being widely used and accepted in clinical practice, the results of individual history items or physical tests do not meaningfully change the probability of ACL injury. In contrast combinations of tests have higher diagnostic accuracy; however the most accurate combination of clinical tests remains an area for future research. Clinical relevance: Clinicians should be aware of the limitations associated with the use of clinical tests for diagnosis of ACL injury.