Background: Because of high consumption of nitrite in processed (fast) foods and high level of nitrite in water, soil and ecosystem, nitrite can endanger humans health. In this study the effects of sodium nitrite on aorta was examined in adult male rats.

Materials and Methods : In the present study, 30 Wistar adult male rats were randomly divided into three groups of 10, including; control group. First experimental group that received low dose of sodium nitrite (175 mg/kg.bw), second experimental group that received high dose of sodium nitrite (350 mg/kg.bw). They were examined for 60 days. The rats got sodium nitrite through drinking water. At the end of the experiment the rats were taken to the anesthesia jar and based on ether principles, they anesthetized with ether and their blood samples were collected from their hearts. Then their aorta were extracted from their bodies and the tissue sections were prepared for testing tissue changes. Features such as histological features of aorta (morphometric and morphologic features) were analyzed. The samples were stained with masson trichrome and Hematoxylin- Eosin methods. The internal media layer was measured with Image tool software. Then the amount of nitrite oxide in their blood were tested. At the end results were analyzed by 17 version of SPSS software and ANOVA test was run.

Results: The results of this study showed that thickness of medial layer in two experimental group that received low and high dose of sodium nitrite compared with the control group decreased (p 0.05), and the group that received of high dose of sodium nitrite showed irregular and non- uniform state in aortic media layer.

Conclusion: The finding of this study indicated that consumption of sodium nitrite in long term can induce damage in artries tissue.