Patients with chronic obstructive pulmonary disease (COPD) who develop community-acquired pneumonia (CAP) may experience worse clinical outcomes. However, COPD is not included as a distinct diagnosis in validated instruments that predict mortality in patients with CAP. The aim of the present study was to evaluate the impact of COPD as a comorbid condition on 30- and 90-day mortality in CAP patients. A retrospective observational study was conducted at two hospitals. Eligible patients had a discharge diagnosis and radiological confirmation of CAP. Among 744 patients with CAP, 215 had a comorbid diagnosis of COPD and 529 did not have COPD. The COPD group had a higher mean pneumonia severity index score (105+/-32 versus 87+/-34) and were admitted to the intensive care unit more frequently (25 versus 18%). After adjusting for severity of disease and processes of care, CAP patients with COPD showed significantly higher 30- and 90-day mortality than non-COPD patients. Chronic obstructive pulmonary disease patients hospitalised with community-acquired pneumonia exhibited higher 30- and 90-day mortality than patients without chronic obstructive pulmonary disease. Chronic obstructive pulmonary disease should be evaluated for inclusion in community-acquired pneumonia prediction instruments.