Background and objective: Gentimicin is an antibiotic from the family of Aminoglycosides used in the treatment of infections resulted from Gram-negative bacteria, the use of which is limited due to its nephrotoxicity. In this study the histological effect of cinnamon on the nephrotoxicity resulted from Gentimicin in rats is investigated because of the Antioxidant properties of cinnamon.Materials and methodology: Thirty-six mature female Wistar rats were divided into six equal groups. The control group did not receive any solvents or medicines. The experimental group I received Gentamicin with the daily dose of 80 mg/kg through intraperitoneal injection, and the experimental group II the daily 200 mg/kg gavage dose of hydroalcoholic extract of cinnamon. The experimental groups III, IV, and V were given the daily dose of 80 mg/kg of Gentamicin through intraperitoneal injection together with 50, 100, and 200 milligrams of cinnamon extract, respectively, by gavage for 21 days. Findings: results indicate that the cortex diameter in experimental groups 1 and 4 increase significantly (P<0.05) compared to control group and experimental groups 2. Diameter of medulla did not increase significantly in different groups. In contrast, diameter of the proximal tubule showed a significant increase (P<0.05) in experimental groups 1, compared to other groups. Also the glomerular diameter in the other experimental groups increased significantly compared to control group and experimental groups 2 .Conclusion: the results of the study show that cinnamon apart from having phenolic compounds and antioxidant properties, can cure the tubular injury resulted from Gentimicin.