There is a never ending discussion on the need for radiotherapy after conservative breast surgery for DCIS (Ductal Carcinoma In Situ). It is true that adjuvant irradiation does not yield any difference in overall survival in the published randomized trials. However, postoperative irradiation after breast conserving surgery (BCS) has been shown to significantly reduce ipsilateral breast event (IBE), whether this is a DCIS recurrence or a recurrence with an invasive component. The real question is to define if there is a subgroup of patients for whom radiotherapy can be withheld without taking any significant local risk. Nowadays, we are not able to define such a subgroup as the possible selection criteria to avoid radiotherapy have never been validated within a well designed prospective randomized trial. Therefore, we think that there is no available evidence to avoid radiotherapy after BCS for DCIS. However, radiotherapy is not indicated after mastectomy.