Background: Cysteinyl leukotrienes have been shown to be important in the pathogenesis of allergen-induced (atopic) asthma and rhinitis. Skin manifestations of atopic dermatitis have been reported to improve with leukotriene antagonists. Montelukast, a newer leukotriene antagonist, which is efficacious and safe in patients with asthma 6 years of age and older, has not been reported as therapy for atopic dermatitis. This article reports findings from a pilot study designed to determine whether montelukast is effective in decreasing the signs or symptoms of atopic dermatitis. Objective: Our purpose was to compare the efficacy of montelukast with placebo as a treatment for patients with atopic dermatitis. Methods: The study involved 8 adult patients (male and female) with at least 1 year of intermittent or persistent atopic dermatitis as determined by Hanifin criteria. Medication was given in a randomized, double-blind, placebo-controlled, crossover manner over 8 weeks as adjunctive treatment. Global evaluation of 6 signs (erythema, induration, excoriation, lichenification, scaling, erosion) were scored on a 0 to 3 scale each week, with a blinded investigator evaluating at the initiation, crossover, and final visit. A 30% decrease in total score was considered clinically significant. Results: A significant difference in atopic dermatitis scores between placebo and active agent (P = .014) was recognized. There was no significant interaction between order and treatment. Atopic dermatitis scores tended to be higher with placebo. The mean standard deviation was 8.7 ± 2.0. The mean for active agent was 6.8 ± 2.1. Conclusion: This study demonstrates that there is a modest, but significant, alleviation of atopic dermatitis with the use of the leukotriene antagonist montelukast used in an adjunctive manner over a 4-week period. (J Am Acad Dermatol 2001;44:89-93.)