Objecive. The investigation is devoted to study subpopulation structure of lymphocytes from peripheral blood of patients, suffering from breast cancer. Materials and methods. Peripheral blood of 70 patients with breast cancer and 39 healthy women was analyzed using the flow cytometry method with monoclonal antibodies to CD3, CD4, CD8, CD16, CD56, CD19, CD45 antigens. Results. Statistically significant disturbance of linear structure of lymphocytes (T-cells CD45+/CD3+/CD19-; B-cells CD45+/CD3-/ CD19+; NK-cells CD45+CD3-CD16+56+) detected only in the analysis of individual immunograms, but not in analysis of whole group of breast cancer patients. Conclusion. Based on analysis of frequence of occurrence of disturbances of cancer breast patients with low values of ratio CD4/CD8, it was detected 4 different variants of disturbance.