PURPOSE: There is increasing awareness of the clinical importance of early detection and treatment of posterior cruciate ligament(PCL) injury. We evaluate the usefulness of Magnetic resonance(MR) imaging in the diagnosis of PCL injury. MATERIALS AND METHODS: We retrospectively analysed the MR images of 140 cases with clinically suspected knee injury. Arthroscopic or surgical correlation was available in 63 cases. We observed the finding and extent of PCL injury and other associated abnormalities. The frequency of anterior and posterior meniscofemoral ligament was evaluated. RESULTS: Eleven PCL injuries were observed, six midsubstance tears, two tibial attachment tears, two fernoral attachment tear, one laxity. The sensitivity, specificity and accuracy of MR imaging diagnosis are 100%, 98.1%, 98.4%. MR findings of PCL injury are discontinuity and focal mass formation, irregular increased signal intensity, detachment or redundancy of the ligament with avulsed bony fragment. In all cases of injured PCL, other associated abnormalities of adjacent structures were observed. Accessory anterior and posterior meniscofemoral ligaments were observed in 67.4%(87/129). CONCLUSION: MR imaging is useful in evaluation of presence or absence of PCL injury, accurate extent of PCL injury and other important associated abnormalities of adjacent structures.