Androgen levels decrease with aging in men. Androgen deficiency in elderly men may lead to asthenia, decrease in muscle mass, osteoporosis, decrease in sexual activity, and, in some cases, changes in mood and cognitive function. Combination of these factors may result in impaired quality of life in the elderly male. Androgen replacement therapy may increase bone and muscle mass, enhance muscle and cardiovascular function, and improve sexual function and general well-being. These potential benefits of androgens have to be weighed against the possible adverse effects on prostate and cardiovascular diseases. Careful long-term studies will be required to assess the risk-to-reward ratios of androgen or other hormone replacement therapy before the development of treatment strategies similar to estrogen and progestagen substitution therapy for the postmenopausal female.