OBJECTIVE We sought to determine the prevalence of 3beta-hydroxysteroid dehydrogenase-deficient nonclassic adrenal hyperplasia among adult hyperandrogenic women with dehydroepiandrosterone sulfate excess. METHODS Thirty consecutive hyperandrogenic women with hirsutism, oligomenorrhea, or both and dehydroepiandrosterone sulfate levels of >8.5 micromol/L and 24 control subjects were studied. Basal sex hormone binding globulin, total and free testosterone, dehydroepiandrosterone sulfate, 17-hydroxyprogesterone, and basal and 60-minute corticotropin-stimulated 17-hydroxypregnenolone and dehydroepiandrosterone were measured, and the increment (change from basal to 60-minute value) was calculated. RESULTS Twenty-six (87%) and 25 (83%) of the 30 hyperandrogenic patients studied had 60-minute dehydroepiandrosterone and change in 0- to 60-minute dehydroepiandrosterone levels greater than the mean + 2 SD of control subjects, respectively. Six (20%) and 6 (20%) of the 30 hyperandrogenic patients had 60-minute 17-hydroxypregnenolone and 0- to 60-minute change in 17-hydroxypregnenolone levels greater than the mean + 2 SD of control subjects, respectively. However, none of the subjects had either 60-minute 17-hydroxypregnenolone levels or 60-minute dehydroepiandrosterone levels or both associated with the diagnosis of genetically proved 3beta-hydroxysteroid dehydrogenase deficiency (>5-fold of the control mean value). CONCLUSIONS 3beta-Hydroxysteroid dehydrogenase-deficient nonclassic adrenal hyperplasia is rare even among adult hyperandrogenic patients with adrenal androgen excess.