Chronic respiratory diseases are among the most common non- infection diseases. In particular, it is bronchial asthma (BA), characterized by bronchial hyperreactivity and varying degrees of airway obstruction that is the cause of morbidity and mortality. The methods available for the information about the presence of inflammation in the airways, such as bronchoscopy and bronchial biopsy to be obtained have currently been invasive and difficult in everyday clinical practice, especially for children and seriously ill patients. In this regard, recently there has been an increase in the development of non-invasive methods for diagnosing the respiratory system, being comfortable and painless for trial subjects, especially children, also providing the inflammatory process control in the lungs, the severity assessment and monitoring the treatment process. The exhaled breath condensate (EBC) is of great attention, which is a source of various biomolecules, including nitric oxide (NO), leukotrienes, 8-isoprostane, prostaglandins, etc., being locally or systemically associated with disease processes in the body. Of particular interest is the presence of cytokines in EBC, namely the specific proteins produced by various cells of the body that play a key role in inflammatory processes in AD and provide cell communication (cytokine network). Thereby, it becomes possible for the severity and control level of childhood bronchial asthma using only the EBC analysis to be assessed. In addition, the non-invasiveness of this method allows it to be reused for monitoring lung diseases of even the smallest patients, including infants. Thus, the field of metabolite analysis in EBC has been developing and, in the near future, the given method is likely to be the most common for diagnosing the respiratory system diseases in both children and adults.