Diabetes mellitus is associated with distribution of cognitive functioning. Hyperglycemia induced oxidative stress has been proposed as a cause of memory complications of diabetes including cognitive impairment. The aim of this study was to examine total green tea extract (TGTE), a potent free radical scavenger against spatial impairment in Streptozotocin-diabetic rats. Eight weeks after diabetes induction, TGTE was administrated throught drinking water 3 mg/L. The learning and memory behavior was evaluated with Morris water maze task in male rats. Then, for estimation of oxidative stress parameters such as lipid peroxidation (LPO), total antioxidant capacity (FRAP) and total thiol groups in blood were measured. The total green tea extract showed improved cognitive impairment in diabetic groups but these changes weren't significant. There was also significant increase FRAP level and total thiol groups in treated green tea groups vs. control. group. This study demonstrated the effectiveness of TGTE on spatial impairment and oxidative stress induced in diabetes mellitus.