The authors examined the action of non-specific bronchial reactivity to methacholine (IBA) before and after treatment with ambroxol in a group of a children with clinic symptomatology of recurrent cough and/or rhinitis. The little patients are selected from a pediatric population that, besides the clinical data mentioned above, had a high probability to manifest nonspecific bronchial reactivity for which clinical and anamnestic data predisposed. In all patients were carried out an allergologic examination with the execution of Prick test and determination of total IgE. The results obtained and discussed suggest a favorable employ of the drug that is able to normalize the functional condition of the bronchial mucous membrane and of the ciliary apparatus which alteration are frequently present in subjects with high non-specific bronchial reactivity.