The present study was performed to evaluate the hypoglycemic and antioxidant effect of aqueous extract of Aegle marmelos leaves (AML) on diabetic rats. Male albino rats were randomly divided into three groups: Group I: Control; Group II: Diabetic rats; and Group III: Diabetic rats administered AML. Glucose, urea and glutathione-S-transferase (GST) in plasma, glutathione (GSH) and malondialdehyde (MDA) levels in erythrocytes were estimated in all the groups at the end of four weeks. There was a decrease in blood glucose at the end of four weeks in group III animals compared with group II, however it did not reach the control levels. There was an increase in erythrocyte GSH and a decrease in MDA in group III as compared to group II. The plasma GST levels were raised in diabetic rats when compared to controls. In the group III animals, there was a decrease in GST as compared to group II. Owing to hypoglycemic and antioxidant properties, AML may be useful in the long-term management of diabetes.