Inflammation and epithelial damage of the bronchial mucosa are frequently identified in children with bronchial diseases. Nevertheless, until now the quantitative assessment of the epithelial damage has never been studied in relation to clinical or respiratory function or mucus abnormalities. Bronchial biopsies and brushings were performed in 31 children with recurrent bronchitis and without atopia. The quantitative histologic data were compared with clinical results, the endoscopic appearance of the mucosa, ciliary beating frequency, mucus transport capacity, leukocyte count, and protein concentration in mucus samples. Most of the biopsies (87%) collected in this group of children without recent acute infections showed extensive epithelial damage. A significant correlation was observed between the degree of shedding and edema (p < 0.01). Bronchial epithelial edema was associated with a significantly decreased (p < 0.01) mucus transport rate. Inflammation of the submucosa was significantly correlated with lymphocyte epithelial infiltration (p < 0.01), total mucus protein content (p < 0.01), and local airway inflammation estimated by bronchoscopy. These results demonstrate that children with recurrent bronchitis develop a severe bronchial inflammation associated with an increased mucus protein content and a reduction in the mucociliary function.