Osteoradionecrosis (ORN) is the common complications of radiation therapy in the head and neck cancer patients. In the history, REGAUD was the first to report about osteoradionecrosis. Later, several criterion are meant for osteoradionecrosis. Several staging or scorings/classifications are given based on clinical findings, radiographic findings, extent of the involvement, response to treatment, etc. Clinically it manifest as ulceration or exposing the necrosed bone or necrosed mucosa. Radiographic features are evident in later stages. We the clinician should be aware and diagnosed early without leading it to further sufferings to the patient.