Abstract: Objective:To compare the adverse reactions of concurrent chemoradiotherapy with docetaxel versus those of sequential and scheduled adjuvant therapy after a modified radical mastectomy in locally advanced breast cancer. Additionally, this work aims to evaluate the safety and feasibility of a synchronous therapy schedule. Methods: A total of 155 female breast cancer patients in the Fourth Affiliated Hospital of Guangxi Medical University were enrolled from January2009 to December 2014 . All the patients were diagnosed with infiltrating ductal carcinoma and stage pT3- 4, pN 1- 3c M 0, or pAnyTpN2- 3cM0 after modified radical mastectomy. After completing the fluorouracil + epirubicin + cyclophosphamide adjuvant chemotherapy, all the patients were randomly divided into two groups by using the method of sealed envelopes. The synchronous group, which received synchronous chemoradiotherapy with docetaxel, comprised 78cases. The sequential group, which received radiotherapy following docetaxel chemotherapy, comprised77 cases. The clinical toxic reactions and effects in both groups were assessed after all schedules. Results:A median follow-up period of 39(16- 62) months showed that the radiation side effects of the synchronous and sequential groups were mild. No patients with3- 4 grade radiation-induced skin reactions or symptoms of heart and lung radiation side effects were reported. The rate of 1- 2 grade radiation-induced skin reactions was 89. 7% (70/78) in the synchronous group and 88.3% (68/77) in the sequential group, but the difference was not statistically significant ( P>0.05). The three-year recurrence-free survival rate was 92.3% (72/78) in the synchronous group and 81.8% (63/77) in the sequential group, and the difference was statistically significant ( P=0.046). Conclusion: Synchronous chemoradiotherapy with docetaxel as adjuvant therapy exhibited mild and tolerable adverse reactions following modified radical mastectomy in locally advanced breast cancer. Compared with the sequential schedule, the synchronous schedule showed a significantly increased three- year recurrence- free survival rate. Therefore, a synchronous chemo -radiotherapy schedule is safe and feasible and can be used as a treatment option for locally advanced breast cancer.