The main objective of the current study was to investigate the effects of titanium dioxide nanoparticles on some Multi-Drug Resistant (MDR) bacteria and consequently, on the liver of male Wistar rats. In this experimental study, nanoparticles in the form of spheres of 20 nm in diameter were synthesized through co-precipitation method, and their antibacterial effect on several bacterial strains was evaluated based on agar well diffusion and macrodilution methods. In addition, the activities of liver enzymes, i.e., ALT, ALP, and AST, and liver tissues in the mice were examined. The obtained data were compared using one-way ANOVA. The results confirmed the ability of these nanoparticles with the concentration of 640 (mg/L) to inhibit the growth of clinical and standard strains of Pseudomonas aeruginosa, Enterococcus faecium, and Staphylococcus aureus. In the case of the activities of liver enzymes AST and ALP, the mentioned concentration of nanoparticles caused a significant decrease in the structure of liver tissue with some disorders. The findings of this study revelaed that these nanoparticles halted the growth of some pathogenic bacteria. However, after intraperitoneal injection into the mice body, the mentioned nanoparticles reduced the activity of liver enzymes and tissue abnormalities.