Erectile dysfunction (ED) is the consistent inability to achieve and maintain an erection sufficient for satisfactory sexual activity. Erectile dysfunction affects as many as 30 million men in America, with an increasing prevalence with age. Erectile dysfunction is secondary to organic, psychogenic and combined causes. The first part of this review article describes the guidelines for evaluation and treatment plans for men with ED. It also describes the normal sonographic anatomy of the penis, sonographic technique for evaluation of ED and the normal phases of erection.