The present study evaluated the effect of mustard oil enriched in capric acid, a medium-chain fatty acid, on antioxidant enzyme activities in liver and brain and on the levels of malondialdehyde (MDA) in liver, brain and plasma in rats; the effect of adding cholesterol to the diet was also investigated. Charles Foster male albino rats weighing 80–100 g were fed one of four diets for 30 d (six rats per group). In the absence of added dietary cholesterol, the addition of capric acid to the diet resulted in lower plasma total cholesterol, non-HDL-cholesterol and TAG concentrations, higher HDL-cholesterol concentrations, higher antioxidant enzyme activities in liver and brain and lower MDA concentrations in liver, brain and plasma. Adding cholesterol to the diet increased plasma total cholesterol, non-HDL-cholesterol and TAG concentrations, decreased HDL-cholesterol concentration, decreased the activities of antioxidant enzymes and increased tissue and plasma MDA concentrations. Including capric acid in the diet of rats receiving cholesterol at least partly prevented the effects of the increased cholesterol. It is concluded that compared with native mustard oil, capric acid-enriched mustard oil improves blood lipids, enhances antioxidant protection and reduces lipid peroxidation.