OBJECTIVE: To define the clinical and radiological characteristics of the patients with injury of the posterior ligament complex of the cervical spine using MR imaging. MATERIALS AND METHODS: Forty patients with acute cervical spine fracture who underwent surgery were examined with MR imaging and plain radiography. Twenty-five patients underwent posterior fusion. The MR findings were correlated with surgical findings, clinical findings, and plain radiographs. RESULTS: Posterior ligament complex injury was detected in 75% (n=30) of all patients. Of the 20 patients with distractive-flexion injury, 90%(n=18) had posterior ligament complex injury (p<0.05). Of the 15 patients with compressive-flexion injury, 73% (n=11) had ligament injury. Of the 4 patients with vertical compression injury, 1 patient (25%) showed ligament injury. One patient with distractive-extension injury did not show ligament injury. Of the 23 patients with complete spinal cord injury, 96% (n=22) showed ligament tear (p<0.05). Of the 17 patients without complete cord injury (15 incomplete injury, 2 no cord injury), 47% (n=8) had ligament injury. Surgical findings were well correlated with MR imaging in patients who underwent posterior surgery (p<0.05). CONCLUSIONS: Injury of the posterior ligament complex in patients with cervical spine fracture was most common in patients with distractive-flexion injury and was more frequent with complete cord injury. MR imaging could reliably reveal such injuries.