Anterior cruciate ligament (ACL) rupture is one of the frequently encountered ligament lesions in the knee. In this injury, which is mostly treated with surgical treatment, the research for the ideal surgical technique continues. In young and active cases, in who conservative treatment is preferred, instability and related to this, additional knee lesions are frequently encountered. Timely implementation of appropriate treatment is important in this regard. To reveal an ACL rupture, beside the mechanism of injury, examination findings, some specific tests and also imaging methods such as MR are used. But none provides precise information. Being positive of one of the specific tests of the Lachman, the Pivot shift, or the recently described Lever tests, is highly suggestive of ACL rupture. More than one positive findings or test increase the probability of diagnosis very much. MR imaging is considered the gold standard in diagnosis. However, rarely, arthroscopic evaluation may also be needed to make the final decision, especially in partial ACL ruptures.