Background: Exposure to ionizing radiation results in genotoxicity and the unrepaired lesions in cellular DNA results in cell cycle arrest, reproductive death, interphase death, division delay, chromosome aberrations, mutations, etc. leading to the intensive destruction of cells and violation of their proliferative capacity there by adversely affecting the mammalian system. Since ionizing radiation is widely used in medicine, industry, agriculture and research, an effective radioprotector is a must to protect living beings. This work aims to identify the ability of dietary supplements, curcumin and ascorbic acid in offering protection from radiation induced genomic insult to human peripheral blood leukocytes. Materials and Methods: Alkaline single cell gel electrophoresis was performed on human peripheral blood leukocytes exposed to 2 doses of gamma radiation in presence and absence of curcumin and ascorbic acid (in vitro). The same technique was also applied to blood leukocytes of volunteers before consumption of these supplements and 5 days after (ex vivo). The comet parameters such as % DNA in tail, tail length, tail moment and olive tail moment were determined. Results: The comet parameters of leukocytes increased upon exposure to ionizing radiation indicating DNA damage, in vitro or ex vivo. The extent of DNA damage was found significantly decreased either in the presence or following the intake of curcumin and ascorbic acid. Curcumin offered higher protection than ascorbic acid. Conclusion: Intake of dietary antioxidants such as curcumin or ascorbic acid could offer protection against ionizing radiation induced cellular DNA damage in peripheral blood leukocytes.