Cell reaction of the stroma of breast tumors is an indicator of the activity of the immunocompetent system in oncological patients. In this work, the cellular response of the tumor stroma was assessed histologically and morphometrically, including calculation of the number of cells-lymphocytes and plasmocytes in the centre of tumor and distally. The intensity of infiltration was estimated quantitatively depending on the type of tumor, patient's age, the presence or absence of regional metastases; moreover the effect of preoperative telegamma-therapy on the tumor stroma was taken into account. The data obtained indicated that the reaction of immunocompetent stromal cells depend on the type of tumor: it is maximum in the stroma of solid tumors and is less pronounced in the stroma of adenocarcinoma and scirrh, and it is minimum in mastopathy. Preoperative irradiation produced no significant reduction in the number of stromal cells. Patient's age rendered no effect on the intensity of cell reactions. The presence of tumor metastases in regional lymph nodes contributed to a fall in the number of stromal cells of solid tumors.