Exodontia of extremely carious teeth leads to a significant risk of osteoradionecrosis in patients who have undergone radiotherapy. In these patients, endodontic treatment could be an alternative. Successful root canal therapy in a girl who had been irradiated for head and neck neoplasms is reported. The results indicated that use of calcium hydroxide to obturate the root canals is a viable method of postirradiation endodontics in primary teeth.