Purpose : The medial meniscus is injured much more than the lateral meniscus. Because the medial meniscus is much larger in diameter, is thinner in its periphery and narrower in body than the lateral meniscus, and does not attach to either cruciate ligament . We evaluated correlations with sites of tear and history of trauma.Materials and Methods We reviewed retrospectively in 43 patients with meniscal tears on MRI(51 cases)and correlated them with history of trauma.Results : The most common site of injury was the posterior horn of the medial meniscus(32/51), but high incidence of lateral meniscal tear compared with previous reports was seen. In the cases which had history of trauma, the posterior horn of medial meniscus was most commonly injured(26/34) and 5 meniscal tears were combined with meniscal tear in the other site. The tear in the anterior horn of the medial meniscus was seen only in a patient which had history of trauma and combined with meniscal tear in the other site. But in the meniscal tears without definite history of trauma, the incidence of meniscal tear was different from the meniscal tear with history of trauma. The incidence of lateral meniscal tear(11/17) was highter than medial meniscal tear and the posterior horn of lateral meniscus was commonly injured.Conclusion : We concluded that the medial meniscus was commonly injured, especially posterior horn, but in the cases which had no definite history of trauma, the lateral meniscus was commonly injured. An awareness of prevalent site of meniscal injuries may be helpful in the diagnostic interpretation of MR imaging of knee.