Since the initiation of radiation therapy in breast cancer in 1940, by radiation alone or radiation combined with surgery, there has been much research about treatment of breast cancer by radiotherapy. These have been a very important place in the treatment of breast cancer, however the effects are still open to controversy. Therefore, the authors analyzed 292 cases of histopathologically proved breast cancer that were treated by radiotherapy at Yonsei University Medical College attached Cancer Center from October 1973 to December 1980, and the 202 patients who were amendable to follow up were analyzed and the results are as follows: 1.The mean age of patients was 47.1 years and localization of the lesion was predominantly in the left and upper quadrant in 40.7%. 2. The chief complaints were painless brest mass in 55.2% of cases. 3. Histopathologically, infiltrating ductal cell ac was found in 93% of cases. 4. The larger the tumor, and the more advanced the staging, there was an increased incidence of axillary lymph node metastases. 5. The 5 year survival in postoperative irradiated cases was 38.8% as calculated by % year survival rate and the survival rate decreased as the stage advanced. 6. The redurrence rate in postoperative irradiated cases was 20.9% and recurrence occured most common in bone. The recurrence and metastases increased as the stage advanced. 7. The recurrence occured on the chest wall most commonly in postoperative patients and metastases in bone and duration to recurrence was shorter than postoperative irradiated patients. 8. The chest wall recurrence was frequently occured in patients whose axillary lymph node was involved with cancer cells than the patients who was not.