Background:renal damage is a common problem in diabetes (D); chronic hyperglycemia is associated with dysfunction in a variety of organs including kidneys. Scientific evidence indicates that medicinal plants comprise a lot of hypoglycemic chemical compounds. Aim of the work: this study aimed to assess the potential ameliorating effect of ethanolic olive leaves extract (OLE) on streptozotocin (STZ) induced D in the renal cortex of adult male rats. This assessment was achieved by biochemical, histopathological and histochemical studies. Materials and Methods: thirty adult Wistar male rats were categorized in three separated groups (10 rats in each group); group 1: control group (C), group 2: diabetic rats (D); streptozotocin was injected intraperitoneally at a single dose of 65 mg/kg b. wt. after 15 minutes of a single dose of nicotinamide which was injected intraperitoneally (230 mg/kg b. wt.), group 3: the diabetic rats which were treated with olive leaf extract (D+ OLE) 15 mg/ kg b. wt. by the gastric tube daily, for 30 days. After one month of treatment, creatinine was measured. Furthermore, histopathological and quantitative histological and histochemical studies were performed. Results: STZ induced a highly significant increase in creatinine level and histopathological changes including desquamation of the epithelial, brush border loss, peritubular infiltration, edematous and hemorrhagic areas, congested vessels and lipofuscin pigments. These pathological findings of the kidney cortex of adult male rats have been reduced by olive leaf extract. Conclusion: use of olive leaf extract should be advised to reduce the hyperglycemic damage to a minimum level.