The purpose of this study was to determine the radiographic findings and clinical significance of the extension corner avulsion fracture (ECAF) of the cervical spine and to defined the role of the plain radiography, computed tomography (CT), and magnetic resonance imaging (MRI) in the evaluation of this injury in order to establish a radiographic protocol. Imaging studies of the cervical spine (including plain radiographs, CT scans, and MRI examinations) and medical records of 31 patients from two major trauma centers were reviewed retrospectively. Twentyeight (90%) of 33 ECAFs occurred at C2. Two patients (7%) had ECAF at more than one level. Ten patients (32%) had additional cervical injuries. Traumatic spondylolisthesis of C2 was the most common associated cervical injury (10%). Seven patients (23%) had associated thoracolumbar injuries. Although all available sagittal reformations demonstrated characteristic fracture, axial CT images failed to demonstrate the fracture in three cases, but, in one patient, they revealed other clinically insignificant fractures not appreciated on plain radiographs. MRI was noncontributory in cases of isolated ECAF. Five patients (16%) had neurologic deficits, with three localized to the cervical region. ECAF occurs most commonly at C2, typically does not result in direct neurologic injury, and is characterized radiographically by a triangular-shaped anteroinferior corner fracture fragment with associated soft tissue swelling. In most cases, ECAF can be adequately assessed by plain radiography. CT and MRI should be reserved for patients with complex fracture patterns or neurologic symptoms.