Adjuvant radiotherapy is well established as the primary modality to enhance local control in breast cancer. The use of adjuvant hormone therapy such as tamoxifen has shown to improve local control to a relatively minor amount on its own and does enhance local control of adjuvant radiotherapy. There is however, conflicting in vitro and clinical data regarding the effects of different sequences on tamoxifen and radiotherapy in terms of both local control and enhancement of radiotherapy toxicities.