Rationale: Exhaled breath condensate pH (EBC-pH) may be useful non-invasive marker for evaluation of asthmatics. Objectives: To investigate the relationship between EBC-pH and symptoms suggestive of childhood asthma in an epidemiological setting and examine its relation to lung function, airway hyperresponsiveness (AHR) and airway inflammation. Methods: Within the context of a prospective, population-based birth cohort, EBC was collected from 630 children at age eight years using the RTube (pH measured after deaeration with Argon). Lung function was measured by spirometry (FEV₁, n=521) and plethysmography (sR_aw, n=567), and AHR by methacholine challenge (n=498). Airway inflammation was assessed using exhaled nitric oxide (eNO, n=305). Results: EBC-pH values ranged widely (4.40-8.29), and did not differ between 54 children with parentally-reported asthma and 562 non-asthmatics (median [interquartile range]: 7.75 [7.45-7.85] vs. 7.77 [7.59-7.87], p=0.35). There was a trend for lower EBC-pH amongst current wheezers (n=98, 7.72 [7.50-7.83]) compared to non-wheezers (n=532, 7.77 [7.60-7.87], p=0.07). Wheeze frequency, severity and use of anti-asthma medication were not associated with EBC-pH. There was no consistent association between EBC-pH and lung function, airway reactivity and airway inflammation (FEV₁, sR_aw, PD₂₀ methacholine or eNO). There was no significant difference in EBC-pH between current wheezers receiving asthma medication who had positive methacholine challenge compared to children without any of these features. Conclusions: In the epidemiological setting, EBC-pH does not differ between children with and without parentally-reported symptoms suggestive of asthma. We found no consistent association between EBC-pH and lung function, AHR and airway inflammation in this sample from the general population.