Oxidative stress is considered as a mechanism of hepatocellular injury in non-alcoholic steatohepatitis (NASH). Pycnogenol (PYC) is the natural plant extract from the bark of Pinus pinaster Aiton. and has potent antioxidant activities. We studied the protective effect of PYC on excessive fat accumulation in the liver fed a methionine-choline deficient (MCD) high-fat diet for 6 weeks. Pycnogenol (10 mg/kg body weight) was orally administered for 5 weeks. At the end of the experiment, blood and liver samples were collected and assessed for effects of PYC by histopathological and biochemical analyses. Histopathological analyses of liver tissues stained with Azan-Mallory showed hepatic macrovesicular steatosis and fibrosis in MCD-fed rats. Supplementation of PYC prevented this effect. Pycnogenol treatment significantly decreased the liver triglyceride and serum alanine amino transferase levels. Our results indicated that orally administered PYC may serve to prevent NASH-induced liver damage.