Technical Abstract: Metabolic syndrome is characterized by insulin resistance, dyslipidemia, and increased oxidative stress. Tea polyphenols, as both insulin potentiating factors and antioxidants, might act in preventing the metabolic syndrome. We aimed to determine the effects of green tea extract consumption on oxidative stress and insulin sensitivity, using fructose-fed diet rats as an animal model of the metabolic syndrome. Wistar rats, 10 per group, received a high fructose diet (FD) for six weeks, or FD plus either 1 or 2 g of green tea solids/kg diet. Signs of the metabolic syndrome (hyperglycemia, hypertriglyceridemia, and hyperinsulinemia) were developed in rats receiving the FD diet compared with those of the control group. Rats receiving added tea solids exhibited an important decrease of glycemia, insulinemia, and triglyceridemia, indicating an insulin potentiating effect of tea. In parallel, oxidative stress was decreased. Significantly lowered plasma lipid peroxidation, sulfhydryl (SH) group oxidation, and DNA oxidative damage were also present. In conclusion, addition of green tea extracts to animals with the metabolic syndrome led to beneficial effects of green tea, both on oxidative stress markers, and on insulin/glucose regulation, indicating that tea may be of benefit to people at risk of the metabolic syndrome and diabetes.