Aim of study — comparison of the eefectiveness and toxicity of low- and high-power brachytherapy used in mono-mode in patients with localized prostate cancer in groups of low and intermediate risk of progression. Material and methods. The study included 226 patients with localized prostate cancer in groups of low and intermediate risk of progression. All patients underwent brachytherapy from 2010 to 2018. 88 patients received treatment in the amount of high dose rate brachytherapy (BT-HPD) using a 192Ir micro source in the form of 2 fractions of 15 Gr with an interval of 2—4 weeks in the Voronezh Regional Oncology Clinical dispensary. 138 patients used brachytherapy using 125Ir microsources (BT-LPD) in standard mode up to a total focal dose of 145 Gr on the basis of the Russian Scientific Center for Radiological Radiology. The median follow-up was 46 months. All patients gave written informed consent. Results. PSA-specific survival was 96.3% in the BT-HPD group and 92.7% in the BT-LPD group. In the group of BT-HPD, as well as BT-LPD, 1 patient with bone metastases was detected, which amounted to 1.1 and 0.7%, respectively. Damage to the lymph nodes in the BT-HPD group was not noted; in the BT-LPD group, 1 (0.7%) case was recorded. In the BT-LPD group, 6 patients with an intermediate risk of progression had a local tumor recurrence. In 5 out of 6 patients, the initial PSA level ranged from 10 to 20 ng/ml. In the BT-LPD group, a higher incidence of early genitourinar (GUT) and gastrointestinal toxicity (GIT) was revealed than in the BT-HPD (p<0.001). The frequency of late GUT in the groups did not significantly differ. Higher results from the side of preservation of erectile function were noted in the BT-HPD group — 74%, BT-LPD — 66.7% (p<0.001). Conclusions. Comparable results were obtained when comparing BT-LPD in patients at low and intermediate risk of progression. Early GUT was more common in patients undergoing BT-LPD. Late GUT in the groups did not differ.