Risk factors for hypoandrogenemia among low-weight, human immunodeficiency virus (HIV)-infected patients are not known. Testosterone levels of 69 HIV-infected women with low weight and weight loss were compared with levels for 25 healthy, age- and body mass index-matched control subjects. HIV-infected subjects were of low weight, with a mean (+/- standard deviation) weight loss of -17.6% +/- 9.7% from preillness maximum, and 42% of HIV-infected subjects had a body mass index of <20 kg/m(2). Forty-nine percent of the HIV-infected population versus 8% of the control population exhibited low free testosterone levels (P<.001). Among HIV-infected women, when we controlled for chronic hepatitis status, age, and time of blood sampling, weight loss of >10% of maximum weight was a significant predictor of low free testosterone levels. Free testosterone levels did not differ by drug class or antiretroviral regimen. In conclusion, decreased androgen levels are common among HIV-infected women reporting significant weight loss, independent of exposure to antiretroviral medications.