Posterior cruciate ligament injuries may occur as an isolated injury or in combination with other ligaments in the multiple-ligament injured knee. Caution must be exercised in chronic posterior cruciate ligament injuries since the MRI may demonstrate a normal-appearing posterior cruciate ligament even when there is significant laxity on clinical examination. Chronic posterolateral or posteromedial instability may also demonstrate significant patholaxity with a normal-appearing MRI. The combination of history, physical examination, magnetic resonance imaging, and arthroscopic evaluation used in combination will maximize the probability for an accurate diagnosis in the posterior cruciate ligament injured knee.