Chronic obstructive pulmonary disease (COPD) is characterized by symptoms of cough, sputum and breathlessness, which become worse during acute exacerbations. The airway inflammation associated with COPD has led to trials of the effect of systemic corticosteroids in COPD assessed in two Cochrane systematic reviews. In stable COPD, compared with placebo, oral corticosteroid treatment increased mean FEV(1) by 53 ml and mean 12-min walking distance by 29 m, but at an increased risk of any drug-related adverse event (OR 7.8). In acute exacerbations, oral corticosteroid treatment decreased the chance of treatment failure (OR 0.48), improved mean FEV(1) at 72 h by 140 ml and improved arterial blood gases, but increased the risk of drug-related adverse events (OR 2.3). Thus, treatment of stable and acute exacerbations of COPD with systemic corticosteroids results in statistically significant average benefits, but at an increased risk of adverse events. In stable COPD, there is little support for the use of systemic corticosteroid treatment, as data on long-term outcomes are lacking. For acute exacerbations, the evidence to support the use of systemic corticosteroids is stronger, but further research is required to define the optimum dose, route and duration.