Nguyen HMT, Gabrielson AT, Hellstrom WJG. Erectile Dysfunction in Young Men - A Review of the Prevalence and Risk Factors. Sexual Medicine Reviews 2017;5(4):508-20. http://www.sciencedirect.com/science/article/pii/S2050052117300501 Introduction - Erectile dysfunction (ED) is an important health concern that can significantly affect a man's psychosocial well-being. ED has traditionally been considered a disease of old age; however, contemporary evidence suggests a growing incidence of ED in men younger than 40 years. The process of achieving an erection is multifaceted; there are many potential mechanisms that can be disrupted. It is critical to identify the specific causes of ED before proceeding with potentially costly and invasive therapeutic options. Advances in diagnostic and treatment modalities offer opportunities to identify and manage young men with ED. Aim - To provide an update on the prevalence and risk factors of ED in young men and to provide a framework to guide clinicians in identifying and managing the affected young man. Methods - Comprehensive review of the literature pertaining to ED in young men. Main Outcome Measures - ED in young men was assessed by outlining the prevalence according to recent epidemiologic studies. The pathophysiology, diagnostic considerations, risk factors, and etiologies were reviewed. Results - Large multinational studies have estimated the prevalence of ED in young men to be as high as 30%. Several studies have stratified the etiologies of ED into psychogenic and organic causes. Psychogenic etiologies of ED include depression, anxiety, and partner-related difficulties. These patients tend to experience sudden onset of symptoms, with decreased libido and good quality of spontaneous or self-stimulated erections. Organic etiologies include vasculogenic, endocrinologic, neurogenic, iatrogenic, and structural components. These patients usually experience gradual onset of symptoms and a low to normal libido. Conservative treatments such as phosphodiesterase type 5 inhibitors continue to be the mainstay treatment. Conclusions - ED in young men is an increasingly common condition. A careful diagnostic evaluation should focus on the identification of any underlying etiology to ensure appropriate management of patients.