Liver is one the vital organs and is involved in the regulation of many physiological activities. Any abnormal liver function creates a set of disorders that can cause irreparable damage to this organ. The goal of this study was investigating the effects of titanium dioxide nanoparticles on liver histology of little laboratory mice. Forty mice were divided into four groups: control group did not receive anything, placebo group, and two experimental groups which received 10 and 100ppm of nanoparticles via gavage. At the end of period liver was colored using hematoxylin eosin method and studied using light microscopy. Obtained data were analyzed using SPSS software. According to results, both 10 ppm and 100 ppm groups caused significant liver pathological which changes were in necrosis form in 100 ppm group. Results showed dose dependent toxicity of titanium oxide nanoparticles