The etiopathogenetic bases of atopic dermatitis are still much discussed and controversial. Nevertheless most of the Authors agree upon the pathogenetic role of an IgE mediated hypersensitivity mechanisms with respect to many alimentary and/or environmental allergens. We have looked for the IgE mediated sensitization to the house dust mites by means of skin tests (prick) and/or haematic dosage of specific IgE (F.A.S.T.) in a group of 40 children aged less than 6 with atopic dermatitis. We have divided the examined children into three groups according to their age and found out a high percentage of dust mites sensitization in the children of the oldest age group. This datum could give credit to the hypothesis of a pathogenetic role developed by the allergy to dust mites in the keeping of eczematous lesions. From the anamnestic search emerge both the leading role developed by dust mites on the development of allergic breathing pathology in the subjects with atopic dermatitis and the finding out of a settled exordium of breathing manifestations due to dust mites at an older age in comparison with the age in which the cutaneous disease manifests itself. These observations lead us to recommend a very accurate environmental cleaning since the first manifestations of atopic dermatitis prescinding from the checking of a demonstrated IgE mediated house dust mites hypersensitivity.