Blood samples were obtained from the spermatic and peripheral veins of 8 males during an operation for inguinal hernia. Three of the subjects were treated with human chorionic gonadotropin (HCG) before collection of the samples. Neutral steroids in the fractions of free, mono- and disulfated compounds were identified and quantified, using gas-liquid chromatography and gas chromatography-mass spectrometry. In addition to testosterone, androstenedione and dehydroepiandrosterone, the following unconjugated neutral steroids were found to be secreted by the normal human testis: 5-androstene-3β,17α-diol, 5-androstene-3β,17β-diol, pregnenolone, 17α-hydroxypregnenolone and 17α-hydroxyprogesterone. In subjects treated with HCG, the concentrations of all these steroids in spermatic vein plasma were considerably higher than in untreated subjects. In addition, considerable amounts of monosulfated pregnenolone, dehydroepiandrosterone and 5-androstene-3β,17β-diol were found to be secreted by the testis in these conditions, whereas the secretion of testosterone sulfate remained unchanged. It is evident that HCG stimulates not only the secretion of unconjugated steroids but also that of certain sulfate-conjugated neutral steroids, which possibly serve as precursors of testosterone in the testis. Testosterone is excreted almost exclusively as the free steroid even in these conditions.