Objective: The aim of our study was to comprehensively access current status of radiotherapy physicians' opinions in post-mastectomy radiotherapy (PMRT) for breast cancer in Guangdong province. Methods: From June 2007 to June 2008, questionnaires on the clinical value, sequencing with chemotherapy and endocrine therapy, indications and irradiated targets for PMRT were sent to physicians of all radiotherapy departments registering at Radiotherapy Professional Committee of Guangdong Anti-cancer Association. Results: There were 126 physicians joining this investigation. Proportions of physicians who accepted the views that PMRT could merely improve local control or can improve both local control and overall survival were 100% and 25.2%. The most common sequences of PMRT and chemotherapy or endocrine therapy were "sandwich" and sequential modes, performed 46.9% and 59.5% respectively. The median interval of surgery and PMRT was 8 weeks. Proportions of physicians who accepted T3–4 diseases, or four or more axillary lymph nodes metastasis, or T1–2 with 1–3 positive lymph nodes, or T1–2N0 with primary tumor located in the center or inner quadrant as the indications of PMRT were 97.6%, 100%, 46.8%, 13.5%, respectively. Proportions of physicians who accepted chest wall, supraclavicular region, internal mammary chain or axilla as irradiated targets were 86.5%, 100%, 49.2% and 38.9% respectively. Conclusion: For Radiotherapy physicians of Guangdong Province, there is still lacking of consensus in the opinions of whether PMRT can improve survival, and optimal sequencing with chemotherapy or endocrine therapy, and how to make decision for patients with T1–2 with 1–3 positive lymph nodes, and rational irradiated targets, which requires advanced professional training for physicians and further prospective clinical trial evidences to guide clinical practice.