The aim of this study was to assess left ventricular diastolic function and forearm endothelial function in patients with erectile dysfunction (ED) without overt cardiovascular disease. Forearm endothelial function and diastolic Doppler parameters, including tissue Doppler imaging, were studied in 32 men with ED and 27 age-matched, healthy, male control subjects. Left ventricular diastolic function in patients with ED and the relation between endothelium-dependent vasodilation and the Doppler parameters of left ventricular diastolic function, including tissue Doppler imaging, were assessed. Endothelium-dependent vasodilation (4.1+/-3.3% vs 9.7+/-4.2%, p<0.001) as well as the mitral inflow E velocity (0.66+/-0.17 vs 0.80+/-0.16 m/s, p=0.01), the E/A ratio (the ratio of mitral inflow E velocity to mitral inflow A velocity; 0.91+/-0.3% vs 1.22+/-0.26%, p<0.001), and the E/Em ratio (the ratio of mitral A-wave velocity to early diastolic velocity in the annulus derived by tissue Doppler imaging; 7.4+/-2.7% vs 6.6+/-1.6%, p=0.03) were smaller in the ED group than in the control group. Deceleration time (228.6+/-61.6 vs 192.9+/-44.6 ms, p=0.03) and isovolumetric relaxation time (112.8+/-18 vs 94+/-15.9 ms, p<0.001) were also prolonged in the ED group compared with the control group. The mitral E-wave velocity (r=0.40, p=0.022), the E/A ratio (r=0.40, p=0.027), and the E/Em ratio (r=-0.52, p= 0.003) were related to endothelium-dependent vasodilation by nivariate analysis. Only the E/Em ratio was correlated with endothelium-dependent vasodilation by multivariate analysis. In conclusion, this study indicates that endothelial function and left ventricular diastolic function are impaired in patients with ED without overt cardiovascular disease.