We previously demonstrated a systemic and topical effect of cyclosporine on hair growth in an experimental model composed of human scalp skin transplanted onto nude mice. The aim of this study was to determine whether topical cyclosporine affects male pattern alopecia. For 4 months in a double-blind study, 10 subjects were treated with cyclosporine and three were treated with olive oil. Hair growth was evaluated by photographs and hair counts. Significant hair growth was observed in two of the eight patients who completed the study. In one the hair growth was cosmetically satisfactory. No systemic or cutaneous side effects were noted.