BACKGROUND: Long-acting beta-agonists and inhaled corticosteroids have been recommended in guidelines for the treatment of chronic obstructive pulmonary disease. However, they have only been available until recently via separate administration. They have been developed in order to facilitate adherence to medication regimens, and to improve efficacy. OBJECTIVES: To assess the efficacy of combined inhaled corticosteroid and long-acting beta-agonist preparations in the treatment of adults with chronic obstructive pulmonary disease. SEARCH STRATEGY: We searched the Cochrane Airways Group chronic obstructive pulmonary disease (COPD) trials register (March 2003), the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 1, 2003), LILACS (all years to March 2003) and reference lists of articles. We also contacted manufacturers and researchers in the field. SELECTION CRITERIA: Studies were included if they were randomised, with adequate blinding procedures in place. Studies could compare a combined inhaled corticosteroids and long-acting beta-agonist preparation with either component preparation or placebo. Studies comparing different members of each class of combined therapies were included DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trial quality and extracted data. MAIN RESULTS: Four randomised trials with 2986 participants were included. Two different combination preparations (fluticasone/salmeterol and budesonide/formoterol) were studied in the trials. No meta-analysis on clinical outcomes was possible due to different outcome assessment across studies. All studies demonstrated a reduction in exacerbation rates versus placebo. Budesonide/formoterol was more effective than formoterol in reducing exacerbations in one study from 1.84 to 1.42 exacerbations per year. Fluticasone/salmeterol did not significantly reduce exacerbations compared with either of its component treatments. Fluticasone/salmeterol led to better quality of life compared with placebo (two studies), although there were conflicting results when compared with inhaled corticosteroid alone (two studies). There was no significant difference between fluticasone/salmeterol and long-acting beta-agonist (two studies). Budesonide/formoterol led to statistically significant differences in quality of life compared with placebo, but not when compared with component inhaled corticosteroid or beta-agonist (one study). REVIEWER'S CONCLUSIONS: For the primary outcome of exacerbations, budesonide/formoterol had a modest advantage over a component medication, formoterol, in a single trial, but fluticasone/salmeterol did not result in a significant reduction in exacerbations compared to either of its components. The combination of steroids and long-acting beta-agonist in one inhaler was effective in improving symptoms compared with placebo and on certain clinical outcomes compared with one of the individual components alone. In order to draw firmer conclusions about the effects of combination therapy in a single inhaler more data are necessary, including the assessment of the comparative effects with separate administration of the two drugs in double-dummy trials.