Introduction The morphofunctional status of the sentinel lymph node (SLN) is a prognostic factor of tumor metastasis. According to the modern concept, lymphagenic metastasis of the tumor is highest in the SLN, and in the absence of metastases in it, the probability of the absence of metastases in other lymph nodes is high. In the era of the development of new immune treatments for breast cancer, the identification of biomarkers that can predict the status of lymph nodes becomes an important task.The aim is immunohistochemical study of the expression level of T- and B-lymphocyte markers in breast cancer in the absence and presence of metastases in them.Materials and methods Sentinel lymph nodes without metastases and with metastases obtained during breast cancer surgery in 18 patients were studied using the immunohistochemical method.Results Comparative morphological analysis revealed that the number of CD3- and CD20-immunopositive cells was significantly higher in the SLN without metastases.Discussions The humoral and cellular immune systems take part in the antitumor immune response. Control over the growth of the tumor is carried out mainly by T cells. The results of our study showed a relatively high level of them in the SLN without metastatic lesion. The information about the antitumor activity of B-lymphocytes is contradictory since both the positive and negative role of B-cells in anticancer immunity is shown. The results of the studies showed that in the case of secondary foci of tumor growth, the number of CD20+ B cells is significantly lower, which indicates the important role of humoral immunity in addition to cell-mediated immunity in breast cancer.Conclusion Quantitative evaluation of (CD3+CD20) cells in the SLN can be used as a possible prognostic marker for breast tumor metastasis.