Abstract: Background and Objective: Hyperglycemia is a representative hallmark and risk factor for diabetes and is closely linked to diabetes associated complications. The aim of the present study was to evaluate the therapeutic potential of exogenous melatonin against the streptozotocin induced pancreatic damages in rats. Materials and Methods: Streptozotocin was injected for consecutive 6 days. Diabetes was confirmed by blood glucose measurement after 72 h and on 7th day after injection. Animals having blood glucose level above 250 mg dL–1 were considered as diabetic and were administered exogenous melatonin for 4 weeks. Animals were euthanized after last dose, pancreas were dissected out, weighed and fixed in Bouin’s fixative for histology and further tissues were kept at -20°C for biochemistry. Results: Diabetic rats displayed significant increase in lipid peroxidation, but pancreatic weight index, antioxidant system (GSH, SOD and CAT) showed decrease. Melatonin treatment to diabetic rats restored the alteration in physiological and biochemical markers. Results were supported by the histopathological observations, STZ treated pancreas showed damage in islets of langerhans, while as melatonin treated diabetic rats recovered the cellular architecture which inturn normalize the function of the pancreas. Conclusion: Therefore, melatonin might be considered as a molecule to protect the pancreatic damages.