A 1% minoxidil topical solution was used to treat 48 patients with alopecia areata, i.e., 24 patients with patchy disease and 24 patients with alopecia totalis or alopecia universalis. Patients (25) had terminal hair regrwoth; in 11 of the 25 patients, it was cosmetically acceptable. No clinical features of the disease seemed to indicate the likelihood of hair regrowth. Hair regrowth began .apprx. 2 mo. after the initiation of treatment and was not uniformly well maintained after the treatment was terminated. One patient had an allergic contact dermatitis reaction to the minoxidil solution; no systemic side effects were seen. No notable systemic absorption was found in 18 adult patients. Effects on cutaneous blood flow or the immune system or some direct effect on hair follicles are possible mechanisms by which minoxidil therapy might stimulate hair regrowth.