Objective. To study the effectiveness and safety of a non-hormonal drug Mastopol® for treatment of various forms of benign mammary dysplasia (BMD) in women of reproductive age. Patients and methods. 168 female patients of reproductive age diagnosed with BMD (group I) and 30 conditionally somatically and gynaecologically healthy women without mastalgia and BMD (control group) were selected. Based on the algologic analysis, patients of group I were stratified into two subgroups. Group IА consisted of 68 patients with BMD and mastalgia, group IB – 70 women with BMD without mastalgia. In groups IА and IB, two subgroups were singled out at random: patients of subgroups А1 (n = 34) and B1 (n = 35) received treatment with a non-hormonal drug Mastopol® 1 tablet 3 times daily sublingually for 8 weeks; patients of subgroups А2 (n = 34) and B2 (n = 35) received a placebo. Clinical and anamnestic data were collected: algological objectification, anxiety assessment using the Spielberger-Khanin, breast ultrasound, determination of serum cytokine levels in peripheral blood by flow cytometry. Study design: a prospective, double-blind, placebo-controlled study. Results. The use of Mastopol resulted in a decrease of the number and severity of clinical signs, improvement of breast sonostructure, a decreased number of cases and less severity of mastalgia, lower anxiety levels, a positive change of cytokine levels. Conclusion. Mastopol® might be a drug of choice for conservative monotherapy in women of reproductive age with BMD and both with mastalgia and without. A high compliance of the drug is conditioned not only by the proven clinical efficacy but also by its excusive safety, good tolerance and convenient use. © 2020, Dynasty Publishing House. All rights reserved.