This study evaluated the toxic effects of titanium dioxide (TiO₂) nanoparticles (NPs) on rats that received oral administration of TiO₂-NPs with a particle size of 15±2nm once daily at doses of 0, 50, 100, 150, 200, and 300mg/kg for ten weeks. Animal mortality, body weight hematology, micronucleus assay and comet assay were investigated. The findings showed that TiO₂-NPs significantly reduced the body weight, and the results indicated a change in all blood parameters due to the stress response of TiO₂NPs. Hematological results revealed that the red blood cell count, hemoglobin, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, white blood cell count, and platelet count  of TiO₂ NPs- treated male rats were altered compared to the control group. However, the WBC of rats was elevated with increased doses of NPs compared with the control. There were no significant differences (P>0.05) in hematological parameters. Comet assay and micronuclei test results show a dosage-dependent increase in DNA fragmentation, which was supported by an increase in percentage of DNA that is tailed, length and intensity of DNA tails, and tail moment, especially at the 300mg/kg dose. According to the findings, the frequency of micronucleated cells has increased.