AIDS: AIDS wasting syndrome (AWS) is a complication of advanced HIV disease characterized by loss of lean body mass. The loss of endogenous anabolic hormones, such as testosterone, is thought to contribute to muscle loss. Studies have shown that more than half of male AIDS patients have low testosterone levels, and increased AIDS severity is correlated with increases in the presence of hypogonadism. Hypogonadism among HIV-infected patients is marked by decreased muscle mass and functional capacity, fatigue, and reduced quality of life. Recently, a 6-month randomized, placebo-controlled trial was conducted on the effects of administering testosterone intramuscularly to hypogonadal HIV-infected men. Patients receiving testosterone experienced significant increases in muscle and lean body mass as well as improved quality of life, appearance, and well being. A 6-month open label extension confirmed a sustained anabolic effect. As an alternative to intramuscular injection, transdermal patches are now available, offering similar benefits and more stable testosterone levels. Transdermal testosterone studies have been initiated in women as well, with promising results. Synthetic testosterone analogues, such as Oxandrolone and nandrolone decanoate, also have been studied in AWS patients. Trials of both resulted in significant weight gain at certain doses, but also demonstrated a significant risk of liver damage. Other anabolic agents are also under investigation.