Combined modality treatments are indicated for most patients with breast cancer. The definition of a proper treatment schedule and of the timing of each modality is a relevant issue that affects the feasibility and the clinical outcome of the treatment. A review of the literature was done on the timing of radiation therapy (RT) in the post-operative treatment of breast cancer. Retrospective studies and randomized clinical trials addressing the issue were considered and grouped according to the combined modality treatments performed. With regard to breast conserving surgery and adjuvant RT, it was verified that a delay up to 8 weeks between breast surgery and start of RT is not associated with an increased risk of local failure if compared with RT started within 4 weeks. Concerning breast conserving surgery followed by adjuvant RT and chemotherapy, the choice of the best schedule is still a complex unresolved issue. More results on sequential schedule of adjuvant RT and chemotherapy from recently published randomized studies are available. The reconstruction of the breast after conservative surgery is rarely necessary and is usually performed immediately after surgical treatment. With regard to mastectomy followed by adjuvant RT and breast reconstruction, it appears from some retrospective studies that autologous tissue transfer offers better results over implants. Concerning the transverse rectus abdominis muscle (TRAM) procedure, either immediate reconstruction before RT or delayed reconstruction after RT was feasible without significative differences in complication rates. Further randomized clinical studies are required to address the unresolved issues linked to the timing of RT. At present the treatment plan should be based on the patient's individual circumstances with regard to risk of metastasis and local failure.