In order to examine whether anti-androgen therapy was effective in hidradenitis suppurativa (HS), ethinyloestradiol 50 micrograms/cyproterone acetate 50 mg in a reverse sequential regimen was compared with ethinyloestradiol 50 micrograms/norgestrel 500 micrograms (Eugynon 50) in 24 female patients. Both treatments produced substantial improvement in disease activity. Seven patients cleared and have remained free of disease for 18 months, five patients improved, four remained unchanged, while two deteriorated. Cyproterone acetate was not clinically significantly more effective than E50, and both gave a similar reduction in free androgen index. Anti-androgen therapy appears to be beneficial in the treatment of hidradenitis suppurativa.