Abstract: Endothelial dysfunction, an important antecedent event in atherosclerosisdevelopment, has been suggested as the common pathophysiologicalfactor between erectile dysfunction (ED) and coronary artery disease (CAD). Flow mediated dilatation (FMD) is frequently used, reliable non invasive marker for endothelial assessment. The present study, we set out to address the relationship of FMD with ED patients undergoing diagnostic coronary angiography. 243 male patients were enrolled in this study. Patients were evaluated by the erectile dysfunction domain of IIEF, a self validated 15 items. There was statistically significant value (P= .0001)between the severe ED patients and extent of CAD. Also the result shows that moderate and severe ED was more in patients with impaired FMD <5.5% as compared to those with normal, FMD > 5.5%. This association was statically significant, P value (<.001). Thus the study finally concludes that functional endothelial abnormality seems to contribute to generalized vascular atherosclerotic process.