[en] In order to examine the usefulness of radiotherapy for verrucous carcinoma, eight cases of oral verrucous carcinoma treated with radiation therapy were reviewed. Definitive radiotherapy was performed in six patients and preoperative radiotherapy was performed in two patients. Definitive radiotherapy doses ranged from 20 to 60 Gy (median: 47.5 Gy) and preoperative radiotherapy doses were 25 Gy, delivered with a daily fraction size of 2.5 Gy in principle. All cases that received definitive irradiation became CR, but two of these patients underwent local recurrence; one was a patient irradiated with only 20 Gy and the other case underwent local recurrence of squamous cell carcinoma. In the cases irradiated with 45 Gy or more, 4 of 5 cases were locally controlled. No patient underwent regional lymph node metastases. One of two patients that received preoperative radiotherapy had local recurrence in spit of a negative surgical margin. Because the radiosensitivity of verrucous carcinoma was often good and anaplastic transformation was not common, radiotherapy can become a radical treatment for verrucous carcinoma. (author)