Glucocorticoids are effective in suppressing androgens in many women whose levels of these steroids are elevated. Their use has been controversial because of inconsistent reports about efficacy and concern about safety. We investigated the dose-response relationship for suppression of dehydroepiandrosterone sulfate (DHEAS) with the use of dexamethasone. Thirty women with an initial DHEAS value of greater than or equal to 300 micrograms/dl were studied. All had cystic or inflammatory acne, hirsutism, or androgenic alopecia. Dexamethasone was given as a single bedtime dosage of 0.125, 0.250, or 0.375 mg. Mean dosage required for suppression was 0.256 mg daily. Suppression of the DHEAS level to less than or equal to 200 micrograms/dl was achieved with 0.125 mg in 25% of women, 0.250 mg in an additional 50%, and 0.375 mg in a further 20%. Most patients were taking spironolactone when the study was performed. Effective suppression is attained with dexamethasone doses significantly lower than previously thought. Use of these doses was not associated with a significant incidence of adverse effects.