Reports suggest that many HIV-infected patients on antiretroviral therapy experience an increase in abdominal fat. The mechanisms of abdominal fat accumulation in HIV-infected patients are not known. Studies have shown: treatment with testosterone gel reduces total body fat in young, androgen-deficient men; testosterone replacement in middle-aged men with mid-segment obesity decreases visceral fat; and replacement doses of testosterone decrease fat mass and augment lean body mass in HIV-infected men with androgen deficiency. Therefore, there is a strong rationale for evaluating the effectiveness of testosterone replacement in HIV-infected men with visceral obesity and low testosterone levels.