Chronic obstructive pulmonary disease (COPD) is a frequent comorbidity in patients with community-acquired pneumonia (CAP). We investigated the impact of COPD on outcomes of CAP patients. We prospectively studied the clinical presentation of 1,379 patients admitted with CAP during a 4-yr period. A comparative analysis of disease severity and course was performed between 212 patients with COPD, as confirmed by spirometry, and 1,167 non-COPD patients. COPD patients (mean forced expiratory volume in 1 s 47.7 ± 16.3% predicted) were older and more likely to have previously received antibiotics (37.1% versus 28.3%; p,0.01) than those without COPD. They presented with more severe respiratory failure (arterial oxygen tension/ inspiratory oxygen fraction 270.4 versus 287.8; p<0.01) and more severe pneumonia (pneumonia severity index 118.3 versus 108.5; p<0.001) compared with non-COPD patients. However, COPD patients had less multilobar infiltration (44 (21%) versus 349 (30%); p<0.01) and fewer pulmonary complications (24 (14%) versus 241 (24%); p<0.01). A total of 89 (6.5%) patients died within 30 days. COPD patients had no significant difference in their 30-day mortality rate compared with non-COPD patients (nine (4.2%) patients versus 81 (7%); p=0.14). Despite worse clinical presentation, COPD patients had a similar mortality rate compared to non-COPD patients. Previous antibiotic treatment and the decreased incidence of pulmonary complications in COPD may account for these findings. Copyright©ERS 2012.