Background: Multiple-organ failure is the main cause of death in diabetes mellitus and hyperglycaemia induced oxidative stress is responsible for major diabetic complications including nephropathy. Medicinal plants with antioxidant activity may modulate oxidative status and improve the functions of multiple organs that affected by chronic hyperglycaemia in diabetes. Aim: The aim of the present study was to investigate on the beneficial effects of saffron aqueous extract (SAE) in streptozotocin (STZ)-induced diabetic rats by measuring the oxidative indicators, functional enzymes and histopathological studies in the kidney tissues. Methods and Material: The fasted rats were injected intraperitoneally (IP) by a single dose of a STZ (60 mg/kg body weight). After 72 hours, the animals with fasting blood glucose over than 250 mg/dl were considered diabetic and were used in the experimental groups; control (1), control drug (2), diabetes (3) and diabetes drug (4). The treatment was started on the 7th day after STZ administration with an IP injection of SAE (200 mg/kg body weight), six doses and weekly to groups (2 and 4). At the end of the experiment, fasting blood glucose, oxidative status and functional enzymes in kidney tissues were measured. Furthermore, histopathological studies were performed. Results: The results showed that SAE significantly decreased blood glucose and prevented weight loss in treated diabetic rats compared to untreated diabetic rats. Moreover, SAE improved oxidative balance and functional enzymes activities in the kidney tissues of Group 4 in comparison to Group 3. Also, histopathological studies showed the less injury in the kidney tissues of treated diabetic rats. Conclusion: Administration of SAE showed significant ameliorative effects on the biochemical, oxidative, and histopathological parameters on kidney tissues of treated diabetic rats.