Objective To provide evidence that could improve management of breast cancer, we conducted a multi-center retrospective epidemiological study to investigate the status of and changes in postmastectomy radiotherapy (PMRT) targets in mainland China.Methods Patients who had received PMRT for breast cancer between 1999 and 2008 were randomly selected from seven hospitals.Information on radiation targets, including the chest wall (CW), the supraclavicular fossa (SCF), the axilla, and the internal mammary chain (IMC) was collected and analyzed.The Cochran-Armitage trend test and the chi-square test were used to compare differences.Results Of 661 included patients, 596 (90.2 %), 606 (91.5 %) 196 (29.6 %), and 297 (44.9 %) had received CW, SCF, axillary, and IMC radiotherapy (RT), respectively.From 1999 to 2008, there was an increase in the use of CW RT (p<0.001), and a decrease in axillary (p=0.027) and IMC (p<0.001) RT.There were significant regional differences in the use of CW (p=0.008), axillary (p<0.001), and IMC (p<0.001) RT.There was no significant change in the use of SCF RT from 1999 to 2008 (p=0.597), or between different regions (,p=0.371).Conclusions Variations in postmastectomy radiotherapy targets existed between different Chinese regions during the period studied.The CW and SCF targets were irradiated in most patients.The use ofaxillary and IMC RT decreased significantly.