The author suggests a direct radioimmunoassay of dehydroepiandrosterone sulfate (DEA-S) in 0.05-2 μ1 of human blood plasma, making use of an antiserum prepared by rabbit immunization with DEA-S hemisuccinate conjugate with bovine serum albumin and [7-3H] -DEA. The method is highly sensitive (0.039 μmol/l), specific, reliable, and easily reproducible. This method was used to measure plasma DEA-S concentrations in healthy subjects of various ages, in women in different phases of the cycle, after dexamethasone load, and in patients with the Stein-Loewenthal's syndrome and the adrenogenital syndrome. It is recommended for the diagnosis of retinopathies connected with adrenal and gonadal androgenic dysfunction.