Objective. In this study, we evaluated the efficacy of simvastatin in the treatment of nonalcoholic steatohepatitis induced by methionine and choline-deficient diet in mice and its possible effect on factors involved in the pathogenesis of the disease including oxidative stress and endoplasmic reticulum stress. Method. Male C57BL6 mice were fed either a normal diet (control) or a methionine and choline-deficient diet for four weeks and then treated orally with simvastatin (4 mg/kg once a day) for two final weeks. At the end of the experimental period, liver integrity, biochemical analysis, hepatic lipids, histology, DNA damage, biomarkers of oxidative stress, and endoplasmic reticulum stress were assessed. Results. Simvastatin treatment was able to significantly reduce hepatic damage enzymes and hepatic lipids and lower the degree of hepatocellular ballooning, without showing genotoxic effects. Simvastatin caused significant decreases in lipid peroxidation, with some changes in antioxidant enzymes superoxide dismutase and glutathione peroxidase. Simvastatin activates antioxidant enzymes via Nrf2 and inhibits endoplasmic reticulum stress in the liver. Conclusions. In summary, the results provide evidence that in mice with experimental nonalcoholic steatohepatitis induced by a methionine and choline-deficient diet, the reduction of liver damage by simvastatin is associated with attenuated oxidative and endoplasmic reticulum stress.