Previous studies have documented that atopic dermatitis can worsen when patients ingest specific foods to which they are sensitive. In this article we demonstrate that patient contact with specific aeroallergens can cause flares of atopic dermatitis. Marked improvement in skin symptoms was noted when 12 patients (eight males and four females; ages, l to 54 years) were removed from their usual environment. In response to prick tests, these patients had markedly positive, immediate wheal-and-flare reactions to a variety of aeroallergen extracts (tree, grass, and weed pollen; house dust mite; animal protein; and mold spores). The same patients were subsequently patch tested on uninvolved, nonabraded skin with the allergen extracts that had yielded positive prick tests. Patch tests were applied for 48 hours, removed, and interpreted 24 hours later. The patients reacted to specific aeroallergens with an eczematous eruption at 48 and 72 hours. Positive delayed cutaneous reactions correlated strongly with aeroallergens identified in the patient's environment or suspected by the patients as provocateurs of their atopic dermatitis. Delayed cutaneous reactions were negative to allergens not historically relevant. Continued avoidance of aeroallergens that elicited an eczematous reaction at patch test sites resulted in marked improvement or resolution of dermatitis in all patients. We conclude that aeroallergen contact plays an important role in select patients with atopic dermatitis.