A total of 351 determinations of sexual hormones were carried out in 189 HIV-infected men in stable clinical condition. Highly active antiretroviral therapy (HAART) was associated with increased levels of both testosterone and 17beta-estradiol, but not with luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Protease inhibitors were more associated with testosterone, and non-nucleoside reverse transcriptase inhibitors with 17beta-estradiol. The values of both hormones, but not those of LH and FSH, increased with respect to pre-treatment levels in those patients who initiated HAART.