Testosterone replacement therapy has been approved in the United States since the 1950s for men with "classical" hypogonadism. These men have specific and well-recognized hypothalamic, pituitary, or testicular conditions leading to deficient or absent endogenous testosterone. A more controversial treatment population is aging men, many with comorbidities, who have low serum testosterone concentrations compared with young healthy men and who do not have the well-recognized medical conditions that cause "classical" hypogonadism. Testosterone continues to be widely used in these men with "age-related hypogonadism" even though the benefits of testosterone for this use are uncertain and there are important risks, including a potential risk of major adverse cardiac events for the testosterone class, and two testosterone products with increases in blood pressure that can increase the risk of myocardial infarction and stroke. Given the uncertain clinical benefit of testosterone in men with "age-related hypogonadism" in the face of known and potential adverse outcomes, none of the testosterone products is FDA approved for such use.