Between 1961 and 1975, 300 women with cancer of the breast (T1:72; T2:167; T3:61) were treated conservatively with radiotherapy alone (T3) or with partial or predominant radiotherapy combined with tumorectomy without axillary dissection (T1 or T2). The results, normalized at 10 years, confirmed that the survival rate (crude or NED) was exactly the same as with other conservative treatments or mutilating surgical treatments. Relapses were few (8%) in T1 cases and acceptable in T2 and T3 cases (13% and 18% respectively); in almost every patient they were amenable to surgery, with good local postoperative course. The prevalence of metastases was directly proportional to the size of the tumour; it was neither more nor less frequent than after radical surgery. Complications were rare and not very severe. Cosmetic results were either excellent (T1) or satisfactory (T2, T3). Finally, the proportions of breasts preserved at 10 years among patients alive and NED was very high, ranging from 96% (T1) to 91% (T2) and 87% (T3). These good results were associated with the possibility of high dosage additional endocurietherapy of the tumoral area with iridium 192, particularly in extensive forms where tumorectomy was cosmetically precluded. Since 1975, we have been using the conservative treatment in closer association with non mutilating surgery.