Chronic inflammatory diseases of the lung are leading causes of morbidity and mortality worldwide. Many of these disorders can be attributed to abnormal immune responses to environmental stimuli and infections. As such, understanding the regulatory systems of innate host defence pathways will be critical to developing new approaches to treatment. In this regard there is increasing interest in the role of microRNA (miRNA) in the regulation of pulmonary innate host defence responses and the inflammatory sequelae in respiratory disease. In this presentation we will discuss recent findings that indicate an important role for miRNA in the regulation of inflammation in mouse models of various respiratory diseases (e.g. asthma) and in host defence against bacterial infection.