Objective: It is known that diabetes leads to depletion of the cellular antioxidant defense system and this causes the organ injuries related to the diabetic complications. Antioxidants have been shown to reduce indices of oxidative stress measures in experimental disease models and in humans. The present study was designed to evaluate the oxidative stress in lungs as well as the therapeutic effect of pomegranate juice (PJ), as an antioxidant, in rats with streptozotocin-induced diabetes. Material and Methods: Twenty seven rats were enrolled in the study where diabetes was induced by streptozotocin injection. Rats were treated with either PJ or saline for 10 weeks, and their lungs were harvested for histologic and immunohistochemical evaluation at the end. Protein carbonyl content (PCC), sialic acid (SA), superoxide dismutase (SOD) and reduced glutathione (GSH) activities were measured in the pulmonary tissue as well as the presence of endothelial nitric oxide synthase (eNOS), through immunohistochemistry. Results: The pulmonary tissue in diabetic rats showed oxidative alterations related to the streptozotocin treatment. There was increased eNOS expressions in diabetic lungs, but PJ treatment diminished both eNOS expressions and inflammatory changes in pulmonary tissue. PCC and SA levels were higher in diabetic lungs (p<0.01) whereas SOD was lower (p=0.021) and GSH did not change significantly in comparison to PJ-treated diabetic group (p=0.374). Conclusion: The PJ treatment effectively reduced the oxidative stress and contributed to tissue recovery in experimental diabetic lungs. These findings would be of clinical relevance.