A thorough history and physical examination are helpful in the diagnosis of meniscal damage, cruciate and collateral ligament sprains and patellar instability, the four major acute knee injuries. When performing a physical examination in a patient with a knee injury, the uninjured knee should always be assessed first and used for comparison. Examination includes passive and active range-of-motion testing, palpation of the joint line spaces, and a variety of maneuvers to evaluate knee stability. Valgus and varus testing provides assessment of the collateral ligaments. The Lachman and pivot shift tests are useful in the evaluation of the anterior cruciate ligament. The posterior drawer and tibial sag tests are used to evaluate the posterior cruciate ligament. The bounce test, McMurray's test and Apley's grind test can aid in the diagnosis of meniscal injury.