Exhaled breath condensate has been more and more extensively used as a novel and non-invasive method to study airway inflammation. It is simple to perform, very well tolerated by patients and no adverse events have been reported so far. Serial measurements can be made with no harmful effects on patients, which is of extreme value in occupational medicine. Exhaled breath condensate has been obtained from both adult and children patients suffering from various pulmonary diseases such as asthma, cystic fibrosis, chronic obstructive pulmonary disease, and interstitial lung diseases. Several markers and mediators are detectable in breath condensate: hydrogen peroxide, thiobarbituric acid-reactive substances, isoprostanes, prostaglandins and leukotrienes. Nitric oxide-related markers have also been studied in the condensate. There is increasing body of evidence that changes in condensate markers reflect local abnormalities of airway lining fluid.