Gamma radiation produces numerous biological perturbations in cells by direct ionization of DNA and cellular targets and by indirect effect through damage by free radical production. The present study has been carried out to investigate the possible therapeutic effect of folic acid loaded magnetic nanoparticles through injection after body gamma irradiation of rats. We have shown that the folic acid loaded magnetic nanoparticles administration reduced the risk factors induced by γ -radiation. 60 male albino rats of about 130-150 g live body weight were divided into six groups, Negative control (n=10), Magnetic control (n=10), folic acid loaded Magnetic NPs control (n=10), and 6 Gy irradiation group (n=10).Three post irradiation groups where these groups exposed firstly to 6 Gy gamma irradiation then injected (I.p) by magnetite NPs, and folic acid loaded magnetic NPs, twice weekly for three weeks. The rats in all groups were anaesthetized, decapitated,the liverwas excised immediately, and frozen at -80 0c. DNA damage in rat hepatocytes were determined by comet assay, and determined cholesterol and triglyceride concentration. Results  showed that  whole body gamma irradiation of rats at 6Gy (single dose) induced significant increase in DNA damage (P < 0.05) that was indicated by increase in tail length, tail DNA% and tail moment as compared to control group. And significant increase in the hepatic cholesterol and triglycerides levels was observed after three weeks post-irradiation Administration of folic acid loaded magnetic iron oxide (Fe3O4) after irradiation induced significant improvement of the DNA damage and hepatic cholesterol and triglyceride level. These results indicate the role of folic acid loaded MNPs as a radio protector agent. Further, we also report the radio protective property of folic acid loaded MNPs as demonstrated by reduction in the radiation induced DNA damage, which was measured by alkaline comet assay.