Background: Asthmatic children present variable degrees of airway inflammation, remodeling and resistance, which correlates with disease control and severity. Chronic inflammatory process of the airways triggers airway remodeling, which reflects the degree of airway resistance. Pro-inflammatory and pro-fibrotic mediators are centrally involved in this process. This study has investigated for the first time, whether the levels of pulmonary and systemic pro-inflammatory and pro-fibrotic mediators present correlation with the resistance of respiratory system and of proximal and distal airways. Methods: 24 asthmatic children (persistent mild and moderate) and 24 non-asthmatic children (both between 6-13 years old) were evaluated for anthropometric characteristics, lung function and mechanics, pulmonary and systemic immune response. Results: Asthmatic children showed an increased number of blood eosinophils (p<0.04), basophils (p<0.04), monocytes (p<0.002) and lymphocytes (p<0.03). In addition, asthmatic children showed an impaired lung function, as demonstrated by FEV1%pred. (p<0.0005) and FEV1/FVC (p<0.004), decreased total resistance of respiratory system (R5Hz; p<0.009), increased resistance of proximal airways (R20Hz; p<0.02), increased elastance (Z5Hz; p<0.02) and increased reactance (X5Hz; p<0.002). Moreover, the following inflammatory factors were significantly higher in asthmatic than non-asthmatic children: GM-CSF in the breath condensate (BC) (p<0.0001) and in the serum (p<0.0001); TGF-beta in the BC (p<0.0001) and in the serum (p<0.004); IL-5 in the BC (p<0.02) and in the serum (p<0.01); IL-4 in the serum (p<0.0002). Conclusions: Impulse oscillometry is a sensitive method to detect airway resistance in asthmatic children, reflecting airway remodeling, an event followed by increased levels of pro-inflammatory and pro-fibrotic mediators.