Androgen deficiency is a common endocrine abnormality among men and women with human immunodeficiency virus (HIV) infection. Low testosterone concentrations are associated with lower CD4 cell count, advanced stage of illness, medication use, and weight loss. Signs and symptoms may be nonspecific. The most useful laboratory indicator is the serum bioavailable (free) testosterone concentration. A number of different testosterone preparations for treatment of androgen deficiency in HIV-infected men now exist. Administration of im testosterone significantly increases weight and lean body mass, energy, quality of life, and depression scores in HIV-infected men with low testosterone levels. Newer transdermal and gel preparations provide more-consistent steady-state dosing but are not as well tested, and sufficient testosterone concentrations may not be achieved with their use. Androgen deficiency is also common among HIV-infected women. Preliminary studies suggest that use of physiological testosterone administration, to achieve testosterone levels within the normal range, is of benefit in HIV-infected women, but further studies are necessary to define the therapeutic role of androgen therapy in this population.