Objective: to study different authors’ data on the variants of evaluation of the resection margins of the breast during organ-sparing surgery for its cancer and to elaborate indications for the procedure to determine the ablasticity of surgery. Material and methods. The authors gave data from different randomized and descriptive studies and studied a relationship between recurrence and resection margin status, as well as 10-year breast cancer recurrence rates in relation to differences in resection margin statuses according to the data on international cancer centers. They considered an association between resection margin status and survival rates; material sampling procedures for resection margin examination; the causes of false-positive resection margins; the false-positive rate of resection margins and the width of resection during organ-sparing surgery; an algorithm of surgical tactics in relation to margin resection status; reasons to make a decision on reoperation for positive or narrow resection margins to exercise local control and to obtain an aesthetic result. Results and control. Reoperation is strictly required for patients younger than 40 years of age, if there is disseminated ductal carcinoma in situ; lymphovascular invasion; no systemic therapy; a few positive resection margins; none data on resection margins; narrow resection margins; and negative prognostic factors. Organ-saving surgery necessitates adequate resection width (at least 10 mm) in order to minimize the risk of local recurrences and to improve overall and relapse-free survival.