The purpose of the work was to study the antimicrobial, antibiofilm-forming, antioxidant and some biochemical properties of alcoholic extracts of Potentilla erecta L. rhizome. The plants for the study were gathered around the village of Luta, Velyky Berezny rayon, Transcarpathia. From the Potentilla erecta L. rhizome, ethyl and methyl extracts were produced. The subjects for study were their antioxidant activity (by DPPH method), total tannin and flavonoids (by spectrophotometric method), and antimicrobial activity (by diffusion-into-agar method). The clinical isolates were isolated with the use of differentially diagnostic nutrient media. The antibiofilm activity of the extracts were tested in standard 96-well microtitration plates. Ethyl and methyl extracts of Potentilla erecta L. rhizome were shown to reveal high antioxidant activity. Antimicrobial activity of the extracts against Staphylococcus genus bacteria and Candida genus fungi was established. The study proved high capacity of ethanol extract for bacterial biofilm destruction. Thus, the study showed the antimicrobial, antioxidant and antibiofilm-forming activity of tormentil ethyl extract against the isolates from the mouth cavities of patients suffering from parodentium inflammatory diseases, which fact contributes to the application prospects of this extract as an active base for mouth cavity hygiene preparations.