An enzyme immunoassay for the quantitative measurement of DHEA-S in serum and plasma. Dehydroepiandrosterone (5-Androstene-3Beta-0L-17-one, Androstenolone, Dehydroisoandrosterone, Transdehydroandrosterone, DHEA) is a steroid hormone present in blood mostly in its sulfate form (DHEA S). DHEA-S is a more specific product of the adrenals and measurements of this steroid are widely used in clinical practice. The clinical importance of plasma assays of DHEA-S is associated with the diagnosis of adrenal hyperplasia and differential diagnosis of hirsutism (1). The DRG DHEA-S ELISA Kit is a solid phase enzyme-linked immunosorbent assay (ELISA), based on the principle of competitive binding. The microtiter wells are coated with a polyclonal antibody directed towards an antigenic site of the DHEA-S molecule. Endogenous DHEA-S of a patient sample competes with a DHEA-S-horseradish peroxidase conjugate for binding to the coated antibody. After incubation the unbound conjugate is washed off. The amount of bound peroxidase conjugate is inversely proportional to the concentration of DHEA-S in the sample. After addition of the substrate solution, the intensity of colour developed is inversely proportional to the concentration of DHEA-S in the patient sample.