Background: Given the high application rate of titanium dioxide (TiO2) nanoparticles in various industries and importance of the liver in body detoxification, the present study reviewed the toxic effects of such nanoparticles on changes of hepatic enzymes and liver and lung tissues.Materials and Methods: In this experimental study, 32 Wistar rats were randomly divided into 4 groups: control (treated with 0.5 mL normal saline) and three experimental groups. Group 1, 2, and 3 received 0.5 mL of solution containing 10, 100, and 300 ppm TiO2 for 7 successive days, respectively. The effects of nanoparticles on serum levels of glutamate oxaloacetate transaminase (SGOT) and glutamate pyruvate transaminase (SGPT) were evaluated at 2, 7, and 14 days. After 14 days, the tissue of liver and lung was collected and investigated.Results: Mean SGOT levels, two days after the intervention, in groups 1 and 3 were significantly greater than the control group. Group 3 had a higher toxicity on hepatic enzymes. The histological results of liver in group 1 showed hepatocyte vasculature and hypertrophy approximate and elimination of hepatic lobules, in group 2 showed, decreased effect of hepatocyte acidophilic and elimination of hepatic lobules, and in group 3 showed, shrinkage of central veins and immediate hyperemia. The histological results in lung, also, showed destruction of alveolus (group 1) and vasculature hyperemia in all groups.Conclusions: It can be concluded that nanometer spherical-shaped TiO2 nanoparticles, even in small amounts for medical purposes, causes cell toxicity. Further research is needed in order to study its effects on organs and blood factors.