The results of radiotherapy were investigated in 49 patients with lung cancer admitted to the Department of Radiology, Okayama University Hospital. Of the 26 patients not undergoing surgery, the one-year survival rate was 100% in the stage I patients, 55% in the stage Ⅲ patients and 56% in the stage Ⅳ patients, and the two-year survival rate was 50% in the stage I patients, 0% in the stage Ⅲ patients and 9% in the stage Ⅳ patients. A significant difference in survival between patients irradiated with over 60 Gy and patients irradiated with less than 60 Gy was recognized among those not undergoing surgery. However, with respect to the frequency of local recurrence and distant metastases, a correlation with the irradiated dose was not demonstrated. Local recurrence and distant metastases were not observed in 5 of 6 patients who received preventive irradiation after curative surgery was conducted. Concerning 11 patients after non-curative surgery, local recurrence and distant metastases were recognized in 3 of them, and 7 of them showed a favourable outcome brought about by the irradiation after surgery as expected. In 6 patients with local recurrence after surgery, the survival period after radiotherapy was less than 13 months.