Background: Injury of the anterior cruciate ligament (ACL) is the most frequently seen ligamentous injury of the knee joint. Diagnosis is based on history, physical examination and MRI findings and a definitive diagnosis is confirmed with arthroscopy. Many tests are used for diagnosis of ACL with different sensitivity and specificity. Objectives: To evaluate lever sign test as a diagnostic tool for ACL injury compared the other 3 tests (anterior drawer, Lachman, and pivot shift test) when performed before anesthesia and under anesthesia. Patients and Methods: The study included 100 patients in the age of 18 to 45 years complaining of knee instability and confirmed as ACL injury by MRI. The 4 special tests for ACL (the Lachman, the anterior drawer, the pivot shift test and the lever sign test) were performed on the injured knee and the contralateral non-injured knee as a control both preanesthesia and under anesthesia. The results were compared to the arthroscopic findings. Results: Lever sign test sensitivity is 72% on examination before anesthesia and 80% on examination under anesthesia with specificity 92%. The most sensitive test Preanesthesia was the Lachman test 88% and postanesthesia was the pivot shift test 89%. The most specefic test was highest for the pivot-shift test 100%. Conclusion: Lever sign test is a simple test which can be routinely used in evaluation of ACL function in both acute and chronic knee injury. The test is weak diagnostic tool in partial ACL injury as it uses pure translational displacement as its assessment method and does not assess the rotational component.