Since 1961, we have treated 400 cases of breast cancers by radical radiotherapy (December 1976). The TNM classification of cases is: 25 per cent T1, 55 per cent T2, 20 per cent T3. 80 per cent of patients are N0 or N1a, 20 per cent are N1b. The therapeutic protocal is: for T1 lesions, lumpectomy plus radical radiotherapy, then boost dose with electrons to the axilla (24 Gy) and to the internal mammaryzone (15 Gy), and finally boost dose to the zone of the breast tumor by Iridium 192 implant therapy (25 Gy);--for T2 and T3 lesions, radiotherapy alone with a higher boost dose to the breast tumoral zone (37 Gy). The mammary tumor (or the tumoral zone) receives a total dose between 70 Gy (T1) and 90 Gy (T2 and T3). The five year results for 328 patients with at least one year follow up (actuarial calculations) yield a survival of 89 per cent T1, 84 per cent T2, and 66 per cent T3. The local recurrences are 8 per cent T1, 10 per cent T2, and 26 per cent T3; they can be rectified, under the condition of regular surveillance, by radical surgery. As to the cosmetic results, they are in one half of the cases quite good, in most others satisfactory, in a few poor. We add a prophylactic chemotherapy in the cases with high metastatic risk, i.e. T3 or N1b cases. This therapeutic protocol seems to be highly recommendable for T1 tumors, acceptable for T2, disputable for T3.