PURPOSE: The purpose of the study was to evaluate the relationship between the location of bone signalabnormality and associated injury, as seen on MR, in patients with acute knee joint injury. MATERIALS AND METHODS: Thirty-six patients with acute knee injury and bone signal abnormalities on MR were included in this study. Thefemur and tibia were each divided into six compartments, namely the anteromedial, medial, posteromedial,anterolateral, lateral, and posterolateral ; these were obtained in each knee joint. We evaluated the location ofbone signal abnormality and the corresponding arthroscopic or operative findings of injury to ligaments andmenisci. Cases with signal abnormalities involving more than three compartments were excluded. RESULT: Bonesignal abnormalities were demonstrated in 51 compartments. Most(84%, 43/51) were noted in the lateral half of theknee joint, the most common location being the tibio- posterolateral compartment(13/51). The femoro-lateral(11/51) and tibio- anterolateral compartment(8/51) were the next most common locations. All cases(13/13)with bone signal abnormality in the tibio- posterolateral compartment had tears at the anterior cruciate ligament,while 9 of 11 cases(81%) with abnormality in the femoro- lateral compartment had tears at the anterior cruciateligament. Six of eight cases(75%) with signal abnormality in the tibio- anterolateral compartment had tears at theposterior cruciate ligament ; 31 of 43 cases (72%) with abnormality in the lateral half of the knee joint hadtears at the medial collateral ligament. Six of eight cases(75%) with signal abnormality in the medial half of theknee joint had tears at the medial meniscus, but no lateral meniscal tear was found. Among patients with signalabnormality in the lateral half of the knee joint, the tear was lateral meniscal in nine of 43 cases(21%) andmedial meniscal in six of 43(14%). CONCLUSION: The location of bone signal abnormality, as seen on knee MR, inpatients with acute knee joint injury could be an important finding suggesting associated injury.