The summation and classification of patients registered for planned radiation therapy in the 24-year period from 1962 to 1986, in the Department of Radiation Therapy, National Cancer Center Hospital, are reported. Patients numbered 16,471, and total sessions of treatment were 26,175. The ratio of the two figures, 1.58, is the average number of treatment sessions per patient. Peak age was 61-65 years' old and 56-60 years old, respectively for males and females. The most frequent primary site of disease for radiation therapy was the head and neck, followed by trachea, bronchus and lung, crevix uteri, breast, and esophagus. Frequency of squamous cell carcinoma was 38.0%; that of adenocarcinoma was 20.9%. Radical treatment was performed in 32.0% of patients in the first session, but this figure decreased to 24.7% for all sessions. There were many cases of secondary and primary palliative treatment, i.e., 31.8%. Radiotherapy was done in 70% of patients by megavoltage X-ray, with 9.4% treated by electron beam. Crude 5-year survival rates for each classification of malignant disease respective to the category of treatment policy from 1962 to 1978 were obtained. Among the radical treatment group, head and neck tumors, skin cancer, and Hodgkin's disease showed 5-year survival rates greater than 50%.