Oxidative stress is currently suggested as a mechanism underyling diabetes. Accordingly, the present study was designed to evaluate the effect of Aralia elate water extracts (AEW) on activities of hepatic oxygen free radical generating and scavenging enzymes in streptozotocin (STZ)-induced diabetic rats. Male Wistar rats divided into nondiabetic group, diabetic group, and diabetic-AEW supplemented group. The extract was supplemented in 1.14% of raw Aralia elata/kg diet for 7 weeks. Diabetes was induced by injecting STZ (55 mg/kg BW, ip) once 2 weeks before sacrifying. The hepatic cytochrome P-450 content, xanthine oxidase and aminopyrine N-demethylase activities were significantly lowered in the diabetic group compared to the nondiabetic group. Whereas, the activities of aniline hydroxylase and oxygen free radical scavenging enzymes, superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glucose-6-phosphate dehydrogenase and glutathione S-transferase, were significantly higher in the diabetic group than in the nondiabetic group. However, the supplementation of AEW normalized these enzyme activities in STZ-induced diabetic rats. When the AEW was supplemented with the diabetic rats, hepatic glutathione content was markedly elevated as well as lipid peroxide level was significantly lowered compared to those of the diabetic group. Thus, these results suggested that AEW supplement enhanced the activities of oxygen species metabolizing enzymes in STZ-induced diabetic rats.