After a total mastectomy in cases of a high risk of loco-regional recurrence the postoperative irradiation of the chest wall is indicated in the following situations: Inflammatory type of carcinoma, tumor stage T3-T4, extended multifocal and multicentric primary tumor. After radical axillary surgery even in patients with positive nodes irradiation is not necessary except in cases where all axillary nodes are involved or with invasion of the axillary tissue. The supra- and infraclavicular lymph drainage regions caudal to the operated area (clip) should be irradiated with 50 Gy providing both an enlarged or subtotal involvement can be diagnosed. The irradiation of the retrosternal lymph-drainage system with 45-50 Gy is indicated as follows: Medial or central tumor site, extensive involvement of the axillary nodes and advanced stages of the primary tumor (T2-T4). Axillary irradiation alone cannot serve as a substitute for surgery. After segmental mastectomy without postoperative radiotherapy a local failure rate of 30% is to be expected during a 5 year period. After surgery with adjuvant postoperative irradiation the local failure rate can be reduced to about 5%: 50-60 Gy should be applied. In case of an unfavourable histology an additional boost dose is recommended. The objective of breast cancer irradiation is to achieve freedom of loco-regional recurrence. The survival can be improved occasionally after local irradiation, theoretically improvement of survival can be achieved in 7-10% at the most.