Erectile dysfunction is often associated with diabetes mellitus and athero-thrombotic diseases, such as coronary heart disease, stroke, peripheral vascular disease. An association between erectile dysfunction and asymptomatic coronary artery disease angiographically verified has been recently shown in diabetic patients. Several pathophysiological mechanisms may explain the relationship between erectile dysfunction and athero-thrombosis, especially in diabetic subjects. Among these mechanisms, it is of interest to consider a common pattern of cardiovascular risk factors, the presence of autonomic neuropathy and endothelial dysfunction. The strong association between erectile dysfunction and athero-thrombosis may have some important clinical implications. In particular, erectile dysfunction may be used as a predictor of silent or early athero-thrombotic diseases, especially in diabetic patients.