This work was directed to evaluate the possible role of silymarin (a flavonoid used as antihepatoxic agent) as a prophylactic agent confronting radiation hazard. Eighty female albino rats were selected at the estrous stage and divided into four groups (G1 - G4): 1- Control. 2- Whole body γ-irradiated group with two doses 1 Gy and 6 Gy. 3- Silymarin orally administered group (10 mg / 100 g b. wt., twice daily for one week with the last dose 2 hours before blood sampling). 4- Silymarin administered as G3 then rats were irradiated after 2 hours. Blood samples were taken at 2 hours, 2 days and 2 weeks after the last silymarin dose (G3) or irradiation (G2 and G4). Irradiation induced significant declines in RBCs and WBCs count, Hg content and Hct % denoting a deleterious effect in a dose and time dependent manner. Yet, it produced high levels of plasma malondialdehyde, as the end product of lipid peroxidation, concomitant with reduced levels of blood glutathione indicating a depression in the antioxidant system. Dramatic increments in the plasma indices of liver (ALT, AST and alkaline phosphatase) and kidney (urea, uric acid and creatinine) functions were also recorded depicting a liver and kidney impairment state. Silymarin manifested good amelioration in the radiation-induced changes in the studied parameters. Hence, it could be concluded that silymarin plays a beneficial radioprotective role against radiation hazard in female rats which serves a great sector of women working in radiation application fields or those undergoing radiotherapy.