The prevalence rate of diabetes mellitus continues to increase all over the world. Medicinal plants constitute an important source of potential therapeutic agents for diabetes. Moringa oleifera has anti-cancer, anti-inflammatory and some researchers reported its hypoglycemic potential. This study aimed to determine the antihyperglycemic effect of dried Moringa oleifera leaves powder of aqueous extract in STZ-induced diabetic male rats and on normal rats as well. Thirty rats were included and divided into 5 groups (6/group). The active ingredients of Moringa oleifera were determined through phytochemical analysis. A significant increase in body weight was found in normal groups treated with Moringa oleifera leaves extract. A significant change was observed in blood glucose and biochemical parameters significant STZ-induced diabetic rats. These changes were reversed by treatment with dried leaves of Moringa oleifera extract. Moringa oleifera leaves or its aqueous extract can reduce reactive free radicals that might lessen oxidative damage and this might be due to rich presence of flavonoids which have antioxidant property. Keywords- Moringa oleifera, STZ, Diabetes