The milk thistle (Silybum marianum) is a good source of phenolic and flavonoid compounds that act as
natural antioxidants. The present study was planned to investigate the protective role of milk thistle (MT)
against γ-radiation (six gray) induced hepatotoxicity and renal toxicity. Liver markers, kidney function, lipid
profile, and malondialdehyde (MDA) as an oxidative stress marker, and antioxidant enzyme (CAT, SOD, and
GSH) were measured after radiation. The obtained results showed that oral administration of milk thistle extract
(200mg /kg B.w) orally daily for four weeks caused significantly decrements in the activities of transaminase
enzymes in the serum of rats, and significantly decrements in the total lipids ,triglyceride and total cholesterol
levels in serum of irradiated rats. Also caused improvement in kidney function, and significant increments in the
antioxidant enzyme (SOD and CAT) and GSH concentration. Significant in decrements total free radical and
MDA in blood and Liver tissues have happened with irradiated groups .This study suggests that (MT) has an
antioxidant effect to radio protective effect, this may be due to its advantage of using (MT) as a source of natural antioxidants against gamma radiation