The coronary arteriosclerotic disease is the most common cardiovascular disease. Atherosclerosis affects large- and medium-sized arteries leading to severe thrombosis or artery stenosis that could evolve to myocardial infarction, ischemic stroke, ischemic injury of kidneys and intestines, and several other life-threatening clinical manifestations. Nitric oxide has been shown to be a promising therapeutic agent against cardiovascular diseases. The eNOS gene assumes several important functions, including regulation of vascular tone and regional blood flow, the suppression of vascular smooth muscle cell proliferation, and modulation of leukocyte-endothelium interactions. The T786C polymorphism is an important point mutation, where thymine is changed to cytosine. T786C significantly reduces the activity of the eNOS promoter gene. Two hundred and ninety-seven peripheral blood samples were collected from patients with the previous diagnosis of atherosclerotic disease based on clinical examination and confirmed by imaging methods. Results were compared using the chi-square test and the G-test. In the present study, the TC genotype was more frequent in both case and control groups with no statistically significant difference. Comparing the relation TC/TT and CC genotypes in the case and control groups, there was no statistically significant difference. No significant difference was found when genotypes were analyzed regarding gender and smoking. Our results suggest a strong tendency of the T allele, in single or double dose, to be associated with atherosclerosis that was not confirmed by the scientific data.