Aim. To study the antibacterial efficacy of the antiseptic drug Miramistin, activated by ultrasound of different frequencies, against pathogenic microorganisms of periodontal pockets, in an experiment. Materials and methods. As an antiseptic drug, the drug Miramistin 0.01% was used, which was activated using ultrasound of different frequencies: high-frequency (880 kHz) in continuous mode for 4 minutes, low-frequency (26.5 kHz) in continuous mode for 2 minutes. To conduct the study, clinical strains of microorganisms obtained from periodontal pockets with moderate periodontitis were used: S. sanguis, S. pyogenes, P. intermedia, C. albicans. The study was carried out using automatic programmable cultivation, using the RTS-8 system. The studied samples of the antiseptic drug were previously diluted in a nutrient broth in a ratio of 2:200. Results. In the course of the study, it was found that with respect to pathogenic microorganisms obtained from periodontal pockets with moderate periodontitis, Miramistin in a dilution of 2:200, activated by low-frequency ultrasound, showed more pronounced antibacterial effect compared to Miramistin activated by high-frequency ultrasound. Conclusions. In the treatment of periodontitis, to suppress the vital activity of pathogenic microorganisms, preference should be given to the combined effects of low-frequency ultrasound and the antiseptic drug Miramistin.