['Sentinel lymph node biopsy (SLNB) without axillary lymph node dissection (ALND) in SLN negative patients is a standard of care for most breast cancer patients. SLNB for axillary staging after primary systemic therapy (PST) is still under discussion because of possibly reduced accuracy, while data are lacking. The purpose of this study was to evaluate the accuracy of SLNB after PST.', 'A total of 185 breast cancer patients were treated with PST; 160 patients received preoperative chemotherapy, and 25 patients received preoperative endocrine therapy. Thus, 143 of 160 patients with preoperative chemotherapy and 22 of 25 patients with preoperative endocrine therapy were eligible for evaluation. The combination of blue dye and radioactive tracer was used for identification of SLNs. All patients received SLNB and axillary lymph node dissection (ALND). Pathologic assessment of SLNs was performed and compared to non-SLN status.', 'Pathologic complete response rates and breast conserving therapy rates were 15.4 and 78.3% in the preoperative chemotherapy group and 0 and 77.3% in the preoperative endocrine therapy group, respectively. Identification rate, sensitivity, overall accuracy, and false-negative rate were 81.1% (116 of 143), 91.7% (55 of 60), 95.7% (111 of 116), and 8.3% (5 of 60) in the preoperative chemotherapy group and 77.3% (17 of 22), 90.0% (9 of 10), 94.1% (16 of 17), and 10.0% (1 of 10) in the preoperative endocrine therapy group, respectively.'] Is sentinel lymph node biopsy precise after primary systemic therapy in stage II-III breast cancer patients?