The safety and efficacy of minoxidil 2% for the treatment of female androgenetic alopecia was assessed in a 32-week double-blind placebo-controlled trial. Thirty-three women aged 22 to 44 years with hair loss classified as Ludwig's grade I or II were enrolled, and 28 completed the trial. Before the administration of treatment, mean nonvellus hair counts were taken within a 1-cm2 target area of the scalp. For the 15 patients in the minoxidil group, the mean count was 169 hairs compared with 161 hairs for the 13 patients in the placebo group. At the completion of the trial, the patients treated with minoxidil 2% had a mean nonvellus hair count of 195 hairs versus a mean hair count of 177 for patients in the placebo group; 60% (9) of the patients in the minoxidil group showed minimal to moderate hair growth compared with 46% (6) of the patients in the placebo group. No serious side effects were encountered during this study, nor any significant changes in safety parameters. There were no dropouts due to medical events related to minoxidil 2%.