Airway inflammation is known to play a crucial role in chronic asthma and has led to the effective use of anti-inflammatory treatments to control chronic asthma. Despite these improvements exacerbations of asthma continue to occur in subjects with stable disease compliant with treatment. Viral respiratory tract infections have been found to be associated with the majority of asthma exacerbations in both children and adults. Evidence is emerging that viral infections may alter the inflammatory infiltrate present in chronic asthma with a more heterogenous neutrophil/eosinophil infiltrate. The implications are that the pathogenesis of acute asthma may differ from that present in chronic asthma in important ways that may influence the effectiveness of treatment. Inhaled corticosteroids are effective in controlling chronic airway inflammation in asthma but appear not to be as effective in acute asthma. This may mean that new directions will be needed to target specifically the airway inflammation in virus-induced acute asthma.