Heterotopic calcification following head and neck irradiation has rarely been reported. It usually develops as a late complication of radiotherapy in patients with malignancies, including breast cancer, lymphoma, and genitourinary malignancies. The occurrence of heterotopic calcification in the prevertebral space of the cervical spine has not been described as a late complication of irradiation. Here, we report a case of prevertebral heterotopic calcification in a patient with history of chemotherapy and radiotherapy for tonsil cancer 21 years ago.