The International Classification of Functioning, Disability and Health (ICF) is a classification used to analyze the results of various interventions and methods for treatment and rehabilitation and to evaluate the functioning of cancer people. Objective — to familiarize surgical oncologists with the concept and structure of the ICF and to use the latter to create the functioning profile in breast cancer (BC) patients who have undergone surgical treatment. Subject and methods. A total of 380 patients aged 30—69 years with stage I—III BC were followed up by the authors for 3 years. Of them, 330 patients underwent the Madden modified mastectomy with axillary lymphadenectomy (ALAE). Fifty patients with T1—2N0M0 breast cancer had the Madden modified mastectomy, by identifying the sentinel lymph node (SLN), without subsequent lymphadenectomy. Results. Based on the follow-up of 330 patients with breast cancer, their functioning problems occurring after the Madden modified mastectomy with ALAE were represented in the terminology of the ICF by 83 second detail level categories and 119 second-third detail level ones: 26 categories for the component of the body’s function, 13 for the structure of the body, 49 for activity and participation, and 31 for environmental factors. In 50 patients with T1—2N0M0 breast cancer after the Madden mastectomy without ALAE, with SLN biopsy, functioning problems were displayed in the terminology of the ICF by 50 second detail level categories and 60 second-third detail level ones: 14 categories for the component of the body’s function, 1 for the structure of the body, 17 for activity and participation, and 28 environmental factors. Sets of ICF codes are given in tables with explanatory notes and methods for estimating some determinants. Conclusion. Since abandonment of regional lymphadenectomy reduces functioning problems, it is extremely important to optimize approaches to surgical treatment for BC.