Background and purpose: Mifepristone is an oral synthetic steroid with antiglucocorticoid and antiprogesterone activities. Therefore, it could be dangerous during pregnancy since it causes cytogenetic damage and, consequently, abortion. Flavonoid compounds such as naringin have antioxidant properties and eliminate various free radicals. Naringin is abundantly found in Iran, so, we investigated its cellular effects against cytogenetic damage caused by mifepristone on blood lymphocyte using micronucleus method. Materials and Methods: In this experimental study, 5ml Venous blood were collected from 5 healthy and non-smokers using heparin syringe. Different naringin concentrations followed by 43µg/ml damage dose of mifepristone were injected to the cells. To evaluate the production of micronucleus in restrained binucleated lymphocytes in cytokine, the slides were prepared and evaluated by optical microscopy. The mean values were compared applying ANOVA test (posttest: Tukey) in SPSS and p