Objective — to preclinically assess whether medical ozone and bacteriophages may be concurrently used in vitro and to also provide a preliminary rationale for a procedure to apply these therapeutic factors in infectious and inflammatory diseases of female genitals. Material and methods. A number of in vitro serial tenfold dilutions of pyobacteriophage were prepared by adding freshly made ozonized isotonic sodium chloride solution at different saturating concentrations of ozone-oxygen mixture (up to 10,000 µg/l) in a nutrient medium (hydrolyzed beef broth). A test tube containing the nutrient medium without bacteriophage and ozonized isotonic sodium chloride solution was used for control. Then 0.03 ml of the daily Escherichia coli, Enterococcus, and Klebsiella suspension culture containing 109 microbial cells were poured into each dilution-containing and control test tube and incubated at 37±1 °C. The activity of pyobacteriophage and its mixture with the ozonized solution was visually estimated from medium transparency. Results. Testing the control samples showed that the pyobacteriophage caused lysis of Enterococcus, Escherichia coli, and Klebsiella in the dilutions of 10–6, 10–5—10–6, and 10–5, respectively. After mixing with ozonized isotonic sodium chloride solution at concentrations of 1500 to 8000 µg/l, the pyobacteriophage preparation of the same series demonstrated no decrease in the activity in any of the samples. Conclusion. Ozone was established to have no significant effect on the activity of bacteriophages, which suggests that their combined local use is possible when treating genital inflammatory diseases. The authors declare no conflicts of interest.