We investigated whether the fermented soymilk extract (FSE) has protective effects against high glucose-induced oxidative stress in human umbilical vein endothelial cells (HUVECs). FSE was prepared via fermentation of soymilk with Bacillus subtilis followed by methanol extraction. To determine the protective effect of FSE, oxidative stress was induced by exposing of HUVECs to the high glucose (30 mM) for 48 hr. Exposure of HUVECs to high glucose for 48 hr resulted in a significant (p<0.05) decrease in cell viability, catalase, SOD and GSH-px activity and a significant (p<0.05) increase in intracellular ROS level and thiobarbituric acid reactive substances (TBARS) formation in comparison to the cells treated with 5.5 mM glucose. However, at concentration of 0.1 mg/mL, FSE treatment decreased intracellular ROS level and TBARS formation, and increased cell viability and activities of antioxidant enzymes including catalase, SOD and GSH-px in high glucose pretreated HUVEC. These results suggest that FSE may be able to protect HUVECs from high glucose-induced oxidative stress, partially through the antioxidative defense systems.