Prevention and treatment of COPD exacerbations are recognized as key goals in disease management. This randomized, double-blind, parallel-group, multicenter study evaluated the effect of fluticasone propionate/salmeterol 250 mcg/50 mcg (FSC 250/50) and salmeterol 50 mcg (SAL) twice-daily on moderate/severe exacerbations. Subjects received treatment with FSC 250/50 during a one month run-in, followed by randomization to FSC 250/50 or SAL for 52 weeks. Moderate/severe exacerbations were defined as worsening symptoms of COPD requiring antibiotics, oral corticosteroids and/or hospitalization. In 797 subjects with COPD (mean FEV(1) = 0.98L, 34% predicted normal), treatment with FSC 250/50 significantly reduced the annual rate of moderate/severe exacerbations by 30.4% compared with SAL (1.10 and 1.59 per subject per year, respectively, p < 0.001), the annual rate of exacerbations requiring oral corticosteroids by 34% (p < 0.001) and the annual rate of moderate/severe exacerbations requiring hospitalization by 36% (p = 0.043). Clinical improvements observed during run-in treatment with FSC 250/50 were better maintained over 52 weeks with FSC 250/50 compared to SAL. Statistically significant reductions in albuterol use, dyspnea scores, and nighttime awakenings and numerical benefits on quality of life were seen with FSC 250/50 compared with SAL. The incidence of adverse events was similar across groups. Pneumonia was reported more frequently with FSC 250/50 compared with SAL (7% vs. 2%). FSC 250/50 is more effective than SAL at reducing the rate of moderate/severe exacerbations. These data confirm the beneficial effect of FSC on the management of COPD exacerbations and support the use of FSC in patients with COPD.