BACKGROUND AND AIMS: Chronic obstructive pulmonary disease (COPD) is associated with substantial morbidity and mortality and is characterised by persistent airway inflammation, which leads to impaired airway function, quality of life and intermittent exacerbations. In spite of recent advances in the treatment of COPD, new treatment options for COPD are clearly necessary. The oral phosphodiesterase-4 (PDE4) inhibitor roflumilast represents a new class of drugs that has shown efficacy and acceptable tolerability in preclinical and short-term clinical studies in patients with COPD. METHODS AND RESULTS: The available long-term clinical studies reviewed here suggest that the clinical efficacy of roflumilast is likely because of the suppression of airway inflammation and not through bronchodilation. Furthermore, the clinical studies have shown a modest improvement in airway function, including FEV(1) , and a reduction in frequency and severity of COPD exacerbations, as well as a positive effect on several patient-reported outcomes. The clinical benefit of roflumilast appears to be greatest in patients with more symptomatic and severe disease who experience exacerbations. The most common adverse effects are gastrointestinal events, primarily diarrhoea, nauseas and weight loss. CONCLUSION: Roflumilast is beneficial for maintenance treatment of patients with severe and symptomatic COPD and with a history of frequent acute exacerbations as an add-on to treatment with long-acting bronchodilators. It may have a role as an alternative to inhaled corticosteroids in more symptomatic COPD patients with frequent exacerbations, although direct comparisons are currently lacking.