Exhaled breath condensate (EBC) is being used increasingly to sample airway lining fluid. In asthmatic patients, the concentration of pH in EBC has been found to be decreased and to be related to airway inflammation. The aim of this study was to determine exhaled pH levels during acute asthma exacerbations in relation to pharmacologic treatment in asthmatic children and compare these with control subjects. Twelve asthmatic children with asthma exacerbation and 27 healthy children were enrolled. Clinical observations and pH in EBC before and after standard treatment for asthma attack, based administration of inhaled beta2-agonist, and corticosteroid, according to international Global Initiative for Asthma guidelines, were compared with those in healthy subjects. All children performed skin-prick tests to aeroallergens. Asthmatic children underwent spirometry. Exhaled pH levels were significantly lower in children with asthma exacerbation before treatment (mean ± SD = 7.87 ± 0.66; p = 0.03) but not after treatment (8.11 ± 0.06; p = 0.40) compared with controls (8.12 + 0.19). Intragroup analyses found that condensate pH levels in asthmatic children before treatment were lower, but not significantly, than those after treatment. No correlation was found between pH values and treatment with systemic corticosteroids or lung function. Asthmatic children were atopic in 75% of cases. Levels of pH are decreased in EBC of asthmatic children with exacerbation before treatment. Larger studies are required to determine whether EBC pH levels may be a useful noninvasive biomarker to guide treatment of asthma exacerbations in childhood.