Abstract: ObjectiveTo evaluate the expression of AR (androgen receptor,AR) in different molecular subgroups of breast cancer and its significance. Methods Three hundred and thirty-five cases of invasive ductal breast carcinoma were involved in this study. Immunohistochemical expression of AR on paraffin-embedded tumor tissues was analyzed，compared with patients' outcome during 66-months' follow-up observation，and its implications were evaluated in five molecular subgroups. Results A greater percentage (72.5%) of breast cancer cases displayed nuclear immunoreactivity for AR，and AR expression was found in 53.2% of ER，PR-negative cases. The majority (61.0%) of basal-like breast cancers showed loss of AR expression，which had poor prognosis. In luminal A，luminal B，basal-like，and normal-like subgroups，the occurrence rate of relapse，metastasis and death for AR positive was lower than that of AR negative tumors (P=0.019，0.044，0.034 and 0.032 respectively). The disease-free survival curves also revealed that the patients with AR expression had a more favorable prognosis than those without it (P=0.006，0.013，0.036 and 0.010). Conclusion The detection of AR may help improve the molecular subtyping of breast cancer and provide theoretical evidence for individualized treatment.