Objective: To study MRI and positron emission tomography (PET)/CT imaging of osteoradionecrosis (ORN) of the subaxial cervical spine, a serious long-term complication of radiation therapy (RT) for head and neck cancers that can lead to pain, vertebral instability, myelopathy and cord compression. Methods: This is a single-institution retrospective review of patients diagnosed and treated for ORN of the subaxial cervical spine following surgery and radiation for head and neck cancer. Results: We report PET/CT imaging and MRI for four patients, each with extensive treatment for recurrent head and neck cancer. Osteomyelitis (OM) and discitis are the end-stage manifestations of ORN of the subaxial spine. Conclusion: ORN of the subaxial spine has variable imaging appearance and needs to be differentiated from recurrent or metastatic disease. Surgical violation of the posterior pharyngeal wall on top of the compromised vasculature in patients treated heavily with RT may pre-dispose the subaxial cervical vertebrae to ORN, with possible resultant OM and discitis. MRI and PET/CT imaging are complimentary in this setting. PET/CT images may be misinterpreted in view of the history of head and neck cancer. MRI should be utilized for definitive diagnosis of OM and discitis in view of its imaging specificity. Advances in knowledge: We identify the end-stage manifestation of ORN in the sub-axial spine on PET/CT and MRI to facilitate its correct diagnosis.