A simple photographic technique was used to assess the objective response of hirsute women to treatment with cyproterone acetate (CA). The skin in front of the left ear was shaved and photographs taken immediately and after 1 week, and hair growth per week estimated by averaging the length of 20 hairs in the magnified photographs. The precision, repeatability and patient acceptance of the method were found to be satisfactory. Basal hair growth rates were 2.28 ± 0.4 mm/week (mean ± SD, n = 34) and showed a significant correlation with hirsutism scores derived from a standard physician-rated scale. During therapy with CA the mean ( ± SD) improvement in hair growth rate was 19 ± 13%, whereas physician-rated hirsutism scores improved by 33 ± 20%. The reduction in hair growth rate showed no significant correlation with improvement assessed using subjective rating by either physician or patient. The greater improvement in physician-rated scores compared with hair growth rate assessment suggests that hair shaft width, colour and other factors may be as important as hair length when assessing treatment response.