A single blind study was planned to investigate whether benzodiapines would reduce androgens in women with idiopathic hirsutism. Placebo was given for the first month followed by four months of a benzodiazepine (chlorazepate 15 mg nocte or diazepam 10 mg nocte ). Plasma samples were collected during the follicular and luteal phases of each therapy month. Hair growth was assessed monthly. Eighteen women concluded the five months of the trial of whom ten received chlorazepate and eight diazepam. Comparison of follicular plasma samples during the placebo phase and fourth month of benzodiazepine found a significant increase in sex hormone binding globulin and a significant decrease in dehydroepiandrosterone sulphate with benzodiazepine therapy. No significant effects on hair growth were observed. A longer therapy time may be needed to demonstrate effects of benzodiapines on hirsutism. Further studies are needed to determine whether benzodiazepines affect hormonal parameters in normal men and women.