Introduction: The present study investigated the beneficial effect of Tanner’s cassia Cassia auriculta flower extract (CFEt) and leaf extract (CLEt) antioxidants properties in streptozotocin (STZ) –induced diabetic rats. Methods: The effects of an aqueous extract of CFEt (0.45 g/kg), CLEt (0.45 g/kg) and glybenclamide on plasma glucose, insulin, thiobarbituric acid reactive substances (TBARS) and hydroperoxides formation, superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase, reduced glutathione, vitamin C and vitamin E, histopathological examination of liver and kidney section of normal and experimental groups. Results: Oral administration of CFEt and CLEt (0.45 g/kg) aqueous extract and glibenglamide to diabetic rats for 45 days significantly resulted in significant reduction in blood glucose and significant increase in plasma insulin levels. In addition, CFEt and CLEt caused significant increase in the activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase, reduced glutathione, vitamin C and vitamin E in liver and kidney of diabetic rats with significant decrease in thiobarbituric acid reactive substances (TBARS) and hydroperoxides formation in liver and kidney, suggesting its role in protection against lipid peroxidation induced membrane damage. Conclusion: CFEt and CLEt possesses antioxidant effect that may contribute to its protective action against lipid peroxidation and enhancing effect on cellular antioxidant defense. This activity contributes to the protection against oxidative damage in Streptozotocin (STZ) induced diabetes. The CFEt administration showed more effective than CLEt and glibencalamide.