A total of 100 children with bronchopulmonary diseases were examined. Of these, in 80 bronchial asthma and in 20 children acute pneumonia were diagnosed. The deficiency of local cell mediated and humoral factors on the mucous membranes of the upper respiratory tracts was established. In the squamous and columnar epithelium cells an increased destruction and cytolysis was noted leading to disturbances in the integrity of the protective barrier of the epithelial cover. In addition, this study revealed the deficiency of neutrophilic leukocytes, pronounced local eosinophilia and the low level of humoral protective factors. In acute pneumonia an increase in the amount of neutrophilic leukocytes in the secretion of the nasal cavity together with the appearance of destructive processes in epithelial cells took place. Pronounced deficiency in serum IgA and IgG was accompanied by compensatory increase in secretory IgA.