To determine whether aeroallergens could induce eczematous lesions, 30 patients with atopic dermatitis were studied in comparison with 30 patients with respiratory atopy without atopic dermatitis. All patients were between 2 and 14 years of age. Patch testing with five aeroallergens--housedust, mite, cockroach, mold mix, and grass mix--was done on skin that was stripped by 10 applications of adhesive tape. Intradermal tests with the same antigens were done on the forearm. In 27 (90%) children with atopic dermatitis, patch testing with aeroallergens induced eczematous lesions at one or more sites. Mite, cockroach, house dust, mold mix, and grass mix caused reactions in 21 (70%), 21 (70%), 19 (63%), 15 (50%), and 13 (43%) patients, respectively. Three patients had a dermatitis flare at the antecubital and popliteal fossae during testing. Only three (10%) atopic children without atopic dermatitis had eczematous lesions, which was significantly different from children with atopic dermatitis (P < 10(-6)). Intradermal skin tests in both groups were not significantly different. This study supports previous reports that aeroallergens plays an important role in causing eczematous skin lesions.