Several inflammatory mediators have been identified in the exhaled breath condensate (EBC) that is formed by breathing through a cooling system. Analysis of EBC is a noninvasive method that allows repeat measurements of lung inflammation and is potentially useful for monitoring drug therapy. Characterization of the profiles of exhaled markers could help to discriminate between different inflammatory lung diseases; thus, EBC might be a novel, noninvasive approach to monitoring lung diseases. However, several methodological issues, such as standardization of sample collection and validation of analytical techniques, need to be addressed before this method can be applied clinically. Controlled studies are needed to establish the utility of EBC markers for guiding pharmacological treatment in inflammatory lung diseases.