Exacerbations of asthma and chronic obstructive pulmonary disease are major burdens on the healthcare system, and contribute significantly to the mortality and morbidity associated with these diseases. Upper respiratory viral infections are associated with the majority of such disease exacerbations. The past few years have seen advances in the mechanisms by which viral infections induce pro-inflammatory chemokine production, and in our understanding of host antiviral and anti-inflammatory defence pathways that might regulate responses to infection. A more comprehensive understanding of the molecular basis of these processes could elucidate new therapeutic approaches to reduce the devastating impact that these exacerbations have on quality of life and healthcare costs.