We performed immunohistochemical analysis of neuroendocrine breast cancer. The significance of this approach to differential diagnosis of this cancer form by detection of specific markers is demonstrated. The incidence of diagnosis of neuroendocrine breast cancer has increased 8-fold over 5 years. Neuroendocrine breast cancer is responsible for 3.4% of all breast cancer cases. The disease is significantly more incident in patients over 60. Neuroendocrine breast cancer is characterized by high expression of neuron-specific enolase (100%) and chromagranin A (57%). The data indicate that irrespective of the location, macroscopic picture, and immunohistochemical profile of cytokeratins and steroid hormones, breast cancer is characterized by clear-cut expression of neuroendocrine markers in different combinations. Immunohistochemical detection of these markers makes it possible to detect the hormone-secreting elements and evaluate their role in the tumor pool, which is essential for the differential diagnosis of neuroendocrine breast cancer, including studies of puncture biopsy specimens.