Male sexual dysfunction refers to a phenomenon in which a man experiences difficulty at any stage during the process of sexual intercourse. In general, erectile dysfunction is regarded as the most representative form of sexual dysfunction, but various other diseases can also be categorized as male sexual dysfunction, including sexual arousal disorder, decreased libido, ejaculation disorder, and Peyronie's disease. Causes of sexual dysfunction include chronic diseases, such as diabetes, hypertension, dyslipidemia, and obesity. In addition, some medications, surgical procedures, and traumas can cause sexual dysfunction. However, aging is the most important cause of male sexual dysfunction. To diagnose and treat elderly patients who complain of male sexual dysfunction, it is first necessary to become familiar with the characteristics of sexual dysfunction in elderly men. The prevalence rates of metabolic syndrome, hypertension, diabetes, dyslipidemia, coronary artery disease, stroke, and depression are higher among elderly men than among younger men; furthermore, the elderly are at a higher risk for the development of kidney, hepatic, spinal cord, and neurological diseases. Notably, anti-hypertensive agents can affect erectile function in elderly men: sexual dysfunction may be severe or the response to treatment may be poor. For satisfactory treatment, spousal factors should also be considered.