Non alcoholic steatohepatitis (NASH) is a pathological condition characterized by accumulation of lipids in the liver of non alcoholic individuals and consequent oxidative stress leading to cirrhosis of liver in the long run. Silymarin is a unique flavonoid complex extract isolated from seeds of the milk thistle plant (Silybum marianum) and has strong antioxidant and radical scavenging properties. The present research aimed to evaluate the therapeutic effects of silymarin (Slym) as natural antioxidant and anti-inflammatory on liver tissue of male rats exposed to experimental model of non alcoholic steatohepatitis (NASH) induced by supplementation of high fat diet (HFD) for 3 months, Through evaluation of serum Alanine Aminotransferase (ALT), Aspartate Aminotransferase (AST), Alkaline Phosphatase (ALP) and Gamma Glutamyl-Transferase (γ-GT) activities and Albumin, Total Protein, Total Bilirubin, Total Cholesterol and triglycerides concentrations. Levels of reduced glutathione (GSH) and activities of Superoxide Dismutase (SOD) and Catalase (CAT), were determined in liver tissues. Extent of oxidative stress was also assessed by hepatic lipid peroxides (MDA). HFD supplementation induced a significant increase in 1) serum ALT, AST, ALP and γ-GT activities, in addition to Total Bilirubin, Total Cholesterol and triglycerides concentrations. 2) Liver MDA concentration. On contrast, it exhibited a significant decrease in serum Albumin and Total Protein, also marked depletion in liver GSH, CAT and SOD, were observed after HFD supplementation. Silymarin treatment was able to mitigate and ameliorate hepatic NASH induced by HFD and showed pronounced curative effect against lipid peroxidation and deviated serum enzymatic variables as well as maintained glutathione status and antioxidant enzymes toward control levels. Silymarin treatment was highly effective against HFD induced NASH. The results of the present study suggest that silymarin has the potential to exert curative effects against liver NASH.