Inhaled corticosteroids have a proven benefit in the management of asthma, but until recently, their efficacy in non-asthmatic, smoking-related chronic obstructive pulmonary disease (COPD) was not evidence-based. Airway inflammation in COPD differs from inflammation in asthma. Some studies have shown an effect of inhaled corticosteroids on airway inflammation in COPD but the clinical relevance of these results are unknown. Short-term studies evaluating the effect of inhaled corticosteroids in patients with COPD were associated with no or modest improvements in lung function. Data from five, long-term, large studies have provided evidence that prolonged treatment with inhaled corticosteroids does not modify the rate of decline of forced expiratory volume in one second (FEV(1)) in patients with COPD and no reversibility to short-acting beta(2)-adrenoceptor agonists. FEV(1) was slightly improved over the first 6 months of treatment in two studies and lower airway reactivity in response to methacholine challenge has been observed. Improvement of respiratory symptoms and health status was also reported in three studies. A reduction in the rate of exacerbations was observed in two studies. No survival benefit was demonstrated in any study. The advantage of using inhaled, rather than oral, corticosteroids is a reduction in adverse effects for the same therapeutic effect, because inhaled corticosteroids rely more on topical action than systemic activity. The long-term safety of inhaled corticosteroids is not known in patients with COPD. However, topical adverse effects, and systemic effects such as a decrease of bone density of lumbar spine and femur and cutaneous adverse effects, have been reported in patients with COPD after 3 years of treatment with inhaled corticosteroids.