During the past decade, evidence has accumulated for the involvement of purines and purine receptors in the pathogenesis and pathophysiology of asthma and chronic obstructive pulmonary diseases. In particular, the indirect bronchospasmic and inflammatory actions of purines via the activation and degranulation of mast cells has been extensively studied and reviewed. At present, interest is focused on the impact of purines on pulmonary innervation and the neuroendocrine system, and the potent interaction of the latter with many of the airway components that are essentially altered in asthma and chronic obstructive pulmonary disease. However, data related to these interactions are diverse and not always easily recognised in the literature.