For many years radiotherapy has been an integral part of the treatment of breast cancer. The focal point of the controversial scientific debate during the past few years was whether besides the undisputed improvement in local control there would also be a positive effect on overall survival. This question can now be considered as largely settled. Several studies conducted during the last few years definitely confirm that the prevention of local relapses can also reduce the risk of distant metastases and enhance the survival rate. These data led to a world-wide re-evaluation of adjuvant radiotherapy. The following article summarizes the essential results of the studies and the recommendations for the established indications.