Erectile dysfunction (ED) is the most common sexual problem in men, after premature ejaculation, affecting up to 30 million in the United States. In a society in which sexuality is widely promoted, ED impacts on feelings of self-worth and self-confidence and may impair the quality of life of affected men and their partners. Damage to personal relationships can ensue; and the anger, depression, and anxiety engendered spill over into all aspects of life. Patients are often embarrassed or reluctant to discuss the matter with their primary care practitioners. Unfortunately, many physicians fail to take the opportunity to promote open discussion of sexual dysfunction. They too, may avoid the topic through personal embarrassment. Since the National Institutes of Health (NIH) Consensus Conference on Impotence in 1992, the inadequate level of public and professional understanding of ED has begun to be addressed. As a first step in breaking down the communication barriers between patients and practitioners, it is important that physicians have a thorough understanding of the wide variety of conditions associated with ED and how the different risk factors for ED may be readily identified. This review addresses the diagnosis of ED and identifies diagnostic tests that can be used by primary care physicians to determine the patients most at risk and the treatments most suited to meet the patients’ and their partners’ goal for therapy.