It is tempting to spare elderly women the burden of adjuvant radiotherapy after breast cancer surgery, even if such a treatment would be justified in light of the available clinical evidence. The reason is that evidence-based radiotherapy derives from clinical trials that excluded elderly women, and that breast cancer is often believed to be more indolent at advanced ages. Unfortunately, the epidemiological evidence, and the few clinical trials recruiting patients over 65 or 70 year of age, all point to the need for postoperative irradiation in a similar set-up as in younger patients. So far, there is no evidence that a subgroup exists in which radiotherapy can be safely omitted. Therefore, the decision to treat or not to treat should be openly discussed with the patient, addressing risks and benefits of both attitudes. Only in frail patients, with an obviously limited life expectancy (months or at most a few years), can omission of radiotherapy be considered, as the burden of local recurrence is likely not to appear before the patient dies from an other cause.