['Hypogonadism is common in human immunodeficiency virus (HIV)-infected men; the high concentration of sex hormone binding globulin (SHBG) in this population, induces a "false increase" in total testosterone (TT) values.', 'To validate the determination of TT and measured free testosterone (FT [radioimmunoassay {RIA}]) for hypogonadism diagnosis in an HIV-infected population using calculated free testosterone (CFT) as reference method; and also to determine the prevalence and identify the risks factors of hypogonadism.', 'Cross-sectional, observational study. Ninety HIV-infected males (42 ± 8.2 years), not HCV coinfected, antiretroviral therapy (ART)-naive (14 patients), on current ART with enhanced protease inhibitor (PI) (39 patients), or patients on PI-naive ART (NN) (37 patients).', "CFT was calculated by determining TT, SHBG, and albumin (Vermeulen's formula); hypogonadism was defined as CFT <0.22 nmol/L (reference range for young healthy males in our laboratory); sensitivity of TT and FT (RIA) for hypogonadism diagnosis was calculated.", "Twelve patients (13.3%, 95% confidence interval [CI] 7.8-21.9) by CFT presented hypogonadism. TT and FT (RIA) presented a sensitivity of less than 30% in the diagnosis of hypogonadism. Logistic regression multivariate analysis confirmed an independent association between hypogonadism, the patient's age per decade, odds ratio (OR) 6.9 (CI 1.9-24.8; P = 0.003), and longer duration of HIV infection per decade, OR 13.1 (CI 1.3-130.6; P = 0.02). Hypogonadism was associated with erectile dysfunction."] Are the determination of total testosterone and free testosterone ( RIA ) applicable to the evaluation of gonadal function in HIV-infected males?