Background: The role erectile dysfunction (ED) coupled with low testosterone levels as early markers of atherosclerosis is not well understood. Objectives: To analyze the relationship between serum testosterone levels with both ED and brachial artery flow-mediated vasodilation (FMD), in a primary prevention sample of men. Methods: We enrolled 802 asymptomatic, intermediate CV risk patients, according to the Framingham Risk Score, aged 40-80 years, who underwent the ultrasound examination of FMD, the evaluation of ED and the assessment of total serum testosterone levels. Results: Testosterone levels correlated both with FMD (r = 0.85; p < 0.0001) and IIEF-5 score (rs = 0.65; p < 0.0001). Multivariable logistic regression analyses revealed that lower serum testosterone levels were strongly associated (p < 0.001) with severe (OR 0.78; 95% CI: 0.62-0.86), and moderate ED (OR 0.85; 95% CI: 0.72-0.97), while impaired FMD percentages were strongly associated (p < 0.001) with severe (OR 0.68; 95% CI: 0.59-0.79), moderate (OR 0.76; 95% CI: 0.63-0.83) and mild to moderate ED (OR 0.8; 95% CI: 0.69-0.94). Mild ED resulted statistically associated with lower FMD (OR 0.94; 95% CI: 0.82-1.07; p = 0.03) but not with serum testosterone levels. These relations were not substantially affected by adjustments for further potential confounders including smoking status, hypertension, diabetes mellitus and body mass index. Conclusions: lower total serum testosterone levels are associated with impaired FMD and ED in this sample of intermediate CV risk men according to the Framingham Risk Score. (C) 2014 Elsevier Ireland Ltd. All rights reserved.