Stress oxidative can cause the development of pathological condition such as diabetes mellitus. Garcinia mangostana L., locally known as “Manggis” is a tropical fruit rich in polyphenolic compounds that possesses high antioxidant activity. This research aimed to study the effect of intake pericarp G. mangostana ethanol extract in inhibiting stress oxidative in hyperglycemic Wistar rats by analyzing superoxide dismutase (SOD) activity and histopathology of pancreatic cell. Extraction of 800 g pericarp Garcinia mangostana with ethanol gave 147 g crude ethanol extract. Hyperglycemic on Wistar rats was made by inducing hyperglycemic with alloxan. The experimental was performed on five groups of animals that were Hyperglycemic. The dose of pericarp of Garcinia extract given to of rats which assigned P0 for normal control, P1 for negative control (hyperglycaemic), P2 for hyperglycemic rats with Garcinia extract 50 mg · kg-1 body weight; P3 for hyperglycemia rats treated with 100 mg · kg–1 body weight and P4 treated with 150 mg · kg–1 body weight. The result showed that intake of pericarp Garcinia extract in all dose given have increased the activity of superoxide dismutase (SOD). The highest SOD activity was obtained in P4 with given of 150 mg · kg–1 body weight and SOD activity increased to 65.71 %. The increased of SOD activity was directly proportional to the histopathology profile of pancreatic found in the hyperglycemic rat.