During the last two decades, significant advances have been made in the understanding of male sexual dysfunction. Concomitantly, a marked increase in both clinical and research activity in the field of male erectile dysfunction has led to a better evaluation and more treatment options. The prevalence and incidence are dependent on the definitions used, the diagnostic tolls, and the treatment options. Using standard definitions as suggested by the NIH Consensus Conference¹⁰⁰ and improving our diagnostic and treatment options¹² will have a major impact on the epidemiology of ED. A summary of the risk factors for ED is presented in Table 3. Still more epidemiologic research is essential to further understand the distribution as well as the prevalence of ED in certain ethnic groups, chronic conditions, and as a result of surgery and trauma. These studies will help us improve our diagnostic skills as well as our therapeutic options.