Background and Objectives: There are several studies conducted to investigate the pathogenesis of diabetic nephropathy, but the obtained results are controversial. It remains one of the most important reasons of mortality in diabetic subjects. Previous researches have indicated that cyclooxygenase 2 (COX2) has an important role in the pathogenesis of diabetic nephropathy. Additionally resveratrol is an herbal polyphenol and it has been beneficial anti-inflammatory effects during short-term administration. This study aimed to investigate the efficacy of long-term resveratrol administration on the activity of COX1, COX2 and nuclear factor kappa B (NF-κB) in diabetic Rats. Materials and Methods: Twenty four male Wistar rats (320-340 g) were randomly divided into four groups (n=6 for each group): normal control, diabetic control, normal rats treated with resveratrol, and diabetic rats treated with resveratrol. Diabetes was induced by injection of streptozotocin (50 mg/kg; i.p.), 15 min after the prescription of nicotinamide (110 mg/kg; i.p.) and resveratrol (5 mg/kg/day) was gavaged for four months. At the end of protocol, blood glucose, insulin, urea and creatinine as well as the activity of renal COX1, COX2 and NF-κB were measured. Results: Four-month resveratrol administrations significantly attenuated the enhancement of blood glucose, urea and kidney to body weight ratio in diabetic rats (p <0.05 for all). Moreover, long-term resveratrol administration to diabetic rats reduced renal COX2 and NF-κB activities. Conclusion: Since the efficient control of blood glucose has a key role in preventing of diabetes complications and in regard to the anti-inflammatory effects of resveratrol in kidneys. It could be considered as a supplementation in preventing of diabetes renal complications.