Some available oral contraceptive agents are unsuitable for the treatment of hirsutism since, although they suppress endogenous gonadotrophins and so ovarian androgen production, they contain a progestogen which is itself androgenic. The combination of 30 micrograms ethinyl oestradiol (EE2) and 150 micrograms desogestrel (Marvelon) does not suffer from this drawback. We have therefore assessed its value in 15 hirsute women treated for one year. Mean +/- SE androgen-dependent hair growth, assessed photographically fell from 0.31 +/- 0.01 to 0.23 +/- 0.01 mm/d at 1 year (P less than 0.001). Ten of the fifteen patients reported definite subjective improvement. Treatment was associated with a marked rise in SHBG concentration identical to that seen with 30 micrograms EE2 alone. By four months there were significant falls in serum levels of androstenedione and LH throughout the cycle, but not for testosterone, dihydrotestosterone or 5 alpha-androstane 3 alpha, beta 17 -diol. Calculated free testosterone levels were significantly suppressed. All the biochemical changes were maintained after seven months of treatment. We conclude that this preparation is a suitable oral contraceptive for the treatment of hirsute women.