The impact of a gaseous ozone-oxygen mixture (OOM) on Mycobacterium tuberculosis (MBT) and opportunistic microorganisms was studied. It was demonstrated that on 15- and 30-min exposure, OOM caused a significant decrease in the number of colonies of the grown microorganisms as compared with the control. The OOM mixture produced the highest effect of the MBT suspension, which is likely to be related to a greater surface of ozone contact with a cell than with a dense medium, and higher concentration of ozone and its highly active radicals that arise from a treatment process. After treatment with a gaseous mixture, 80-90% of the microbial cells lost their reproductive ability. The strains grown after OOM action retain drug sensitivity of the original strain. The results suggest that the use of a gaseous OOM mixture is promising in the treatment of tuberculosis to cleanse the destruction cavities and pleural empyemas, including those of nonspecific etiology.