Current research endeavours indicate that adenosine elicits strong inflammatory responses in the lung and might be involved in the pathogenic mechanisms of chronic inflammatory disorders of the airways such as asthma and chronic obstructive pulmonary disease (COPD). The contribution of adenosine-associated effector mechanisms to the initiation, persistence and progression of the inflammatory response is highly heterogeneous and is dictated by the expression pattern of four different adenosine receptors. Selective activation or blockade of these sites can therefore be exploited in an attempt to generate novel therapies for asthma and COPD. In addition, an important development is the use of adenosine (or AMP) as a diagnostic test for discriminating asthma from COPD, and as an accurate biomarker to monitor corticosteroid requirements in asthma. It is likely that therapies interfering with adenosine signalling in the airways will offer a considerable advance in the management of asthma and COPD.