Aims: Coronary endothelial dysfunction(CED) precedes atherosclerosis and is associated with cardiovascular events. Both CED and erectile dysfunction(ED) are partly mediated by impairment in the nitric oxide pathway. ED is associated with established coronary atherosclerosis, but its relationship with early coronary atherosclerosis and CED is unknown. This study was designed to test the hypothesis that CED is associated with ED in men with early coronary atherosclerosis. Moreover, the role of the nitric oxide synthase inhibitor asymmetric dimethylarginine(ADMA) was investigated; ADMA is a novel endogenous competitive inhibitor of nitric oxide synthase and has been shown to be an independent marker for cardiovascular disease. Methods and results: Fifty-six men without obstructive coronary artery disease(CAD) who underwent coronary endothelial function testing were studied. ADMA levels were determined and all men were asked to complete the International Index of Erectile Function-5 questionnaire to assess erectile function. Patients were divided according to the presence(n=32) or absence(n=24) of CED. Men with CED had significant impairment of erectile function(P=0.008) and significantly higher ADMA levels(0.50± 0.06 vs. 0.45± 0.07 ng/mL, P=0.017) compared with men with normal endothelial function. Erectile function positively correlated with coronary endothelial function. This correlation was independent of age, body mass index, high-density lipoprotein, C-reactive protein, homeostasis model assessment of insulin resistance index, and smoking status. Conclusion: CED is independently associated with ED and plasma ADMA concentration in men with early coronary atherosclerosis. This study further supports the role of the endothelium in systemic vascular diseases and the role of ADMA in the systemic manifestations of endothelial dysfunction. Both CED and erectile dysfunction (ED) are partly mediated by impairment in the nitric oxide pathway. ED is associated with established coronary atherosclerosis, but its relationship with early coronary This study was designed to test the hypothesis that CED is associated with ED in men with early coronary atherosclerosis. Moreover, the role of the nitric oxide synthase inhibitor asymmetric dimethylarginine (ADMA) was investigated; ADMA is a novel endogenous competitive inhibitor of nitric oxide synthase and has been shown to be an independent marker for cardiovascular disease. Methods and results: Fifty-six men without obstructive coronary artery disease (CAD) who underwent coronary endothelial function testing were studied. ADMA levels were determined and all men were asked to complete the International Index of Erectile Function-5 questi Men with CED had significant impairment of erectile function (P = 0.008) and significantly higher ADMA levels (0.50 ± 0.06 vs. 0.45 ± 0.07 ng / mL, P = 0.017) compared with men with normal endothelial function. This correlation was independent of age, body mass index, high-density lipoprotein, C-reactive protein, homeostasis model assessment of insulin resistance index, and smoking status. Conclusion: CED is independently associated with ED and plasma ADMA concentration in men with early coronary atherosclerosis. This study further supports the role of the endothelium in systemic vascular diseases and the role of ADMA in the systemic manifestations of endothelial dysfunction.