Introduction: Hyperglycemia is a common signature of Diabetes Mellitus (DM) which could define as fasting blood glucose higher than 110 mg/dL or 2-hour post prandial blood glucose higher than 180 mg/dL. One of the consequences of hyperglycemia is increased rate of the oxidative process that could potentially damage many organs. The damage could be assessed by measuring 8-Hydroxy-2 Deoxyguanosine (8-OHdG) that represent the damage of the plasma membrane. In this study, we aimed to evaluate the efficacy of Syzygium polyanthum leaves extracts as antioxidant agent on hyperglycemic Wistar rats. Methods: 40 Wistar rats were used in this study. Hyperglycemic state was achieved by administration of alloxan for two weeks for each rat. 3 Kg of S.polyanthum leaves was used for extraction which yields 0,730 ethanol extract. The rats were divided into positive control, P1 (alloxan only), P2 (Alloxan+ 0.5 mg kg-1 body weight Z polyanthum extract), P3 (Alloxan+ 2.0 mg kg-1 body weight Z polyanthum extract), P4 (Alloxan+ 5.0 mg kg-1 body weight S.polyanthum extract), P5 (Alloxan+ 0.18 mg/day/ kgbody weight glibenclamide). Result: The result shown that the rats which received S.polyanthum extract had significantly lower blood glucose level (65.91 % lower than control) and lower level of 8-OHdG (50.20% lower than control). The effective dose to optimally lower blood glucose and 8-OHdG was found at 5,0 mg kg-1. Conclusion: S.polyanthum ethanolic leaves extract was an effective anti-hypoglycemic and antioxidant agent with optimal dose found at 5,0 mg kg-1.