Background. Breast cancer (BC) is not only a global medical problem, but a social problem associated with its steady growth and spread. Thus, the prevalence of BC in women in Russia in 2021 was 21.1 %. Combined or complex treatment is used in the vast majority of cases (surgery, drug and radiation therapy); in 2021, this percentage was 64.5 %. Currently, there is no doubt that radiation therapy is necessary as part of the complex treatment of patients with T1–3N1–2 BC, as it leads to an increase in survival rates. The development of reconstructive plastic surgery makes it possible to restore the removed breast using implants or autologous tissues. Reconstruction with endoprostheses is the main method, it accounts for up to 70 % of all reconstructive breast surgeries. Until recently, the most popular method was a two-stage reconstruction. Especially in cases where radiation therapy is planned. However, our own experience of one-stage reconstructions in combination with radiation therapy showed good aesthetic results with a low complication rate, which was the reason for this study.Aim. To study and compare the incidence of complications in one- and two-stage breast reconstruction after subcutaneous/skin-sparing mastectomy in combination with radiation therapy.Materials and methods. A prospective study of 92 patients diagnosed with BC was carried out. The patients were divided into 2 groups: group I (study) included 50 women, who underwent one stage – subcutaneous/skin-sparing mastectomy with breast reconstruction using an implant, II (control) group included 42 patients, who underwent subcutaneous/skin-preserving mastectomy with breast reconstruction with an expander, followed by replacement of the expander with an implant. After radiation therapy, the groups underwent a comparative assessment of anthropometric and anamnestic data, a study of the somatic anamnesis, the results of pathomorphological typing of the tumor, treatment tactics and complications.Results and conclusion. Subcutaneous/skin-sparing mastectomy with simultaneous breast reconstruction using an implant does not increase the incidence of postoperative complications when combined with radiation therapy, and also does not limit the appointment of concomitant treatment methods in the complex therapy of women with BC. This method of surgical treatment can be used in patients with IIA, IIB and IIIA stages of tumor growth.