BACKGROUND : An acceptable algorithm for clearance of the cervical spine (C-spine) in the obtunded trauma patient remains controversial. Undetected C-spine injuries of an unstable nature can have devastating consequences. This has led to reluctance toward C-spine clearance in these patients. OBJECTIVE : To objectify the accuracy of computed tomography (CT) scanning compared with dynamic radiographs within a well established C-spine clearance protocol in obtunded trauma patients at a level I trauma center. METHODS : This was a prospective study of consecutive blunt trauma patients (18 years or older) admitted to a single institution between December 2004 and April 2008. To be eligible for study inclusion, patients must have undergone both a CT scan and dynamic plain radiographs of their C-spine as a part of their clearance process. RESULTS : Among 402 patients, there was one injury missed on CT but detected by dynamic radiographs. This resulted in a percentage of missed injury of 0.25%. Subsequent independent review of the CT scan revealed that in fact pathologic changes were present on the scan indicative of the injury. CONCLUSIONS : Our results indicate that CT of the C-spine is highly sensitive in detecting the vast majority (99.75%) of clinically significant C-spine injuries. We recommend that CT be used as the sole modality to radiographically clear the C-spine in obtunded trauma patients and do not support the use of flexion-extension radiographs as an ancillary diagnostic method.