Introduction. Airway inflammation is a common feature of many diseases. Its repercussions can be discovered in many aspects of the disease, therefore finding the biomarker or combination of biomarkers to define it continues to be challenging. The scientific material and methods used are the review of current literature data, controversies, discordances and peculiarities of respiratory tract inflammation and biomarkers capable to assess it. The results are centered on those biomarkers capable to capture inflammation from as many angles as possible, with impact not only on the pathogenesis of the disease but also with clinical, evolution, therapeutic and monitoring implications. Conclusions. For airway inflammation many biomarkers are useful, some define the disease as a whole, some are defining for certain aspects or endotypes. The winning combination proposed by many authors appears to be a panel of biomarkers which captures as many aspects as possible for each entity, but is usually difficult to find.