Abstract This study aimed to investigate the prognostic value of AR in HER2+ nonmetastatic breast invasive ductal carcinoma (IDC) and its relationship with the immune microenvironment. HER2+ nonmetastatic breast IDC patients diagnosed by pathology who underwent surgery at Sun Yat-sen University Cancer Center from 2016 to 2017 were included. AR+ and AR− breast IDC samples were matched 1:1 in age, T stage, and N stage for immune infiltration analysis. A total of 554 patients with HER2+ nonmetastatic breast cancer were included in this retrospective study, regardless of HR status. The cut-off value for AR was set at 10%. ER+ (p