Background: Axillary lymph node dissection is a redundant method of surgical treatment and axillary staging for a large number of patients receiving neoadjuvant therapy with positive lymph nodes before NCT. Methods: The study included 212 patients with breast cancer (cT1-3N1M0) who received treatment at the breast tumors department of the N.N. Petrov NMRC of Oncology from 2019 to 2021 All patients included in the study had the cN1 initial status of the axillary lymph nodes. All patients underwent neoadjuvant systemic therapy and subsequent sentinel lymph node biopsy (SLNB). In patients with pathomorphologically proven metastatic lymph nodes (cN1) even at the initial diagnosis, lymph node marking was performed before the start of NCT and targeted axillary lymph node dissection after the completion of neoadjuvant systemic therapy. In the same patients, after SLNB and targeted axillary lymph node dissection, a complete (standard) axillary lymph node dissection was performed to determine the false-negative rate and the oncological safety of the procedure. Results: The identification rate of only one sentinel lymph node was 21% (40 out of 193 patients), two sentinel lymph nodes - 30% (58 out of 193 patients), more than 3 - 49% (95 out of 193 patients). When only 1 sentinel lymph node was found, the false-negative rate of SLNB was 20.0% (4 of 20) (95% CI, 5.7 to 43.7). When two sentinel lymph nodes were found, the false-negative rate of SLNB was 20.0% (6 of 30) (95% CI, 7.7 to 38.6). When three sentinel lymph nodes were found, the false negative rate of SLNB was 4.7% (2 of 43) (95% CI, 0 to 15.8). Among 45 patients who had a microseed with the iodine-125 radioisotope installed before the start of treatment, the frequency of identifying a marked node was 100%. In 19 patients, tumor cells were found in the lymph nodes. The false-negative rate of targeted axillary dissection in combination with SLNB was 5.3% (1 of 19) (95% CI, 0 to 26.0). Conclusions: Targeted axillary dissection and sentinel lymph nodes biopsy, provided that 3 SLNs are removed, are reliable methods for identifying patients in whom systemic therapy is guaranteed to achieve complete response of regional lymph nodes (ypN0), thereby relieving patients of the need to perform a crippling complete axillary lymph node dissection. Clinical trial information: 3/198.