PURPOSE: To analyze various MR imaging findings and thus evaluate the usefulness of MR imaging of the tem-poromandibular joint in patient with acute mandibular condylar fracture. MATERIALS AND METHODS: MR imaging was performed within 1week after trauma in 25 patients (total joints s-tudied=31) in whom condylar fracture had been diagnosed by simple radiographs. We analyzed the signal intensity of bone marrow and disk, displacement of bone fragment and disk, deformity. In addition, MRI findings of retrodiskal tissue, joint capsule and joint effusion were eualuated. RESULTS: No abnormal signal intensity was noted in bone marrow or disk. Displacement of a condylar fracture fragment was observed in 24 joints(77 %) (anteromedial, 63 %; medial, 25 %; anterior, 4%; anterolateral, 4 % ; and lateral, 4 %). Disk displacement occurred in 23 joints(74 %) (anteromedial, 65 %; medial, 9 %; anterior, 18%; anterolateral, 4 %; and lateral, 4 %). In 17 joints (55 %) the disk was displaced along with the fractured condylar fragment, and disk deformity was noted in five joints(16 %). MR imaging (T2WI) revealed a capsular tear(n=1), joint effusion(n=26), and high signal intensity in the retrodiskal tissue(n=6). CONCLUSION: MR imaging provided information concerning condylar fragments, disks, retrodiskal tissue, capsules, and joint effusion. In patients with acute mandibular condylar fracture, MRI is therefore useful for evaluation of the temporomandibular joint.