Abstarct: The Purpose of this Study is to use Ozone Micro Nano Bubble Technology to remove bacterial species of nosocomial infection. For this purpose, samples from species of the 4 bacteria namely Enterococcus faecalis, Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa were placed in direct contact with Ozone Micro Nano Bubbles (OMNB) and ozone gas (For comparison) at ambient temperature of 37 C°. Samples were cultured at different time contacts. The results showed that generally, with increasing concentration of inlet ozone, removal time of the studied bacteria were decreased. The removal efficiency of bacteria by OMNB is significantly increased compared to the usual ozonation at the same concentration. Enterococcus faecalis, Escherichia coli and Staphylococcus aureus confronted with OMNB at a concentration of 10g/h were completely removed in less than 1 minute while Pseudomonas aeruginosa resisted for 90 seconds before total removal. In the same concentration of ozone by ordinary porous diffuser, Enterococcus faecalis, Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa were removed after 10, 12, 22 and 22 minutes. By decreasing the ozone concentration the removal time was increased. At both concentrations of 1.7 and 5 g/h of ozone gas, Enterococcus faecalis was removed in 60 minutes, Escherichia coli and Staphylococcus aureus also were removed after 90 minutes of ozonation with diffusers. Time of Complete removal of Pseudomonas aeruginosa was also measured; 130 minutes in 1.7 g/h ozone and 120 minutes for 5 g /h of ozone. In the case of OMNB at concentration of 1.7 g/h, water containing Enterococcus faecalis, Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa respectively was completely disinfected at contact times of 8, 8, 10 and 22 minutes. Mentioned bacteria were completely removed during treatment with OMNB at a concentration of 5 g/h after 2, 3, 5 and 8 minutes. It was observed that the fastest removal at all concentrations of ozone belongs to Enterococcus faecalis and the longest removal time was for Pseudomonas aeruginosa. According to the results of this study, disinfection of water contaminated with these bacteria can be effectively performed by the use of OMNB to accelerate and increase the efficiency of the disinfection process.