Objective: Ionizing radiation (IR) induces DNA damage on normal cell leads to genotoxicity. The radioprotective effects of co-treatment curcumin and piperine were investigated against genotoxicity induced by ionizing radiation in human normal lymphocytes. Material and methods: Human blood samples were pretreated with curcumin at different concentrations (5, 10 and 25 µg/ml) and/or piperine (2.5 µg/ml) and then were exposed to IR at dose 1.5 Gy. The radioprotective effects of curcumin and piperine were assessed by micronucleus (MN) assay. Results: It was found that curcumin and piperine reduced the percentage of MN induced by IR in lymphocytes. Piperine alone significantly reduced genotoxicity induced by IR as compared to curcumin alone at all concentrations. An additive radioprotective effect was observed in combination of piperine and curcumin at low concentration 5 µg/ml while this synergistic effects were not observed with curcumin at higher concentrations 10 and 25 µg/ml. Conclusion: This result provides that piperine acts as a potent radioprotective effect at low concentration as compare to curcumin. However, an additive radioprotective effect was observed with co-treatment piperine and curcumin at low concentration, while piperine increased the percentage of MN in normal lymphocytes when was co-treated with curcumin at higher concentration.