With an aim to examine the effect of ethanolic extract of P. crispum (Parsley) leaves on the D-galactose-induced oxidative stress in the brain of mouse, the activities of antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase) involved in oxygen radical (OR)-detoxification and antiperoxidative defense were measured in conjunction with an index of lipid peroxidation in mitochondrial fraction of various regions of the mouse brain. A significant decrease in superoxide dismutase and glutathione peroxidase activity was observed in D-galactose-stressed mice, while catalase activity was increased. Treatment of D-galactose-stressed mice with the ethanolic extract of P. crispum showed protection against the induced oxidative stress in brain regions. Concentration of thiobarbituric acid-reactive product was greatly elevated in D-galactose stress-induced mice and was significantly reduced in the brain regions of these mice upon treatment with P. crispum. It is postulated that parsley shows a protective effect against mitochondrial oxidative damage in the mouse brain.