 Background By means of measurements of series of non-invasive inflammatory markers in exhaled breath condensate, a reflection of inflammatory processes and oxidative stress, can be obtained. Thereby, these techniques could be important in monitoring asthma and CF lung disease in children. Fractional exhaled nitric oxide FeNO and inflammatory markers in exhaled breath condensate EBC reflect ongoing inflammation and oxidative stress in the airways. These markers have a promising capacity for monitoring diagnoses of CF and asthma lung disease. 