Objective: Endothelial dysfunction is an early marker of atherosclerosis. Angiotensin II and nitric oxide have important roles in maintaining the vascular tone. The existence of the angiotensin converting enzyme (ACE) gene polymorphisms has been known, and deletion (D) of the allele has been associated with coronary artery disease. As ACE genotype affects endothelial functions in the patients with risk factors for coronary artery disease, it may also be a determinant of atherosclerosis. In this study, the relationship between endothelial function and ACE gene polymorphisms was investigated in healthy young subjects. Materials and Methods: Forty-six healthy young subjects were included in this cross-sectional, randomized study. Participants were further divided into three groups according with ACE genotypes: DD genotype - 24 subjects, DI genotype - 13 subjects and II genotype - 9 subjects. All patients underwent brachial artery ultrasonographic examination. We analyzed ACE insertion (I) and D allele frequencies in all subjects. Kruskal-Wallis test was used to compare continuous variables, and the Chi-square test was used to compare proportions among groups. Results: Demographic features were similar except gender between the groups according to the ACE genotypes. Total cholesterol levels were lower in the DD genotype comparing with the others (pİ0.05). High-density lipoprotein cholesterol levels, baseline brachial artery diameter, baseline blood flow and the increase in the blood flow during the reactive hyperemia were also similar. The changes in flow-mediated dilatation (endothelium dependent) were 4.9±1.3% in DD genotype, 5.5±1.7% in DI genotype and 5.5±1.9% in II genotype groups. Flow mediated dilatation was lower in DD genotype group as compared with ID and II genotype groups, however, this result did not reach statistical significance (p>0.05). Endothelium independent dilatations were similar among different ACE genotypes. Conclusion: Our data showed that ACE genotype has no effect on endothelial functions in patients without risk factors for coronary artery disease.