Despite the apparent common occurrence of pneumonia in patients with chronic obstructive pulmonary disease (COPD), there are little firm data on incidence, etiology, diagnostic procedures, and therapy in these patients. It appears that traditional respiratory pathogens such as the pneumococcus are declining in importance while "new" pathogens such as Pseudomonas sp., Moraxella catarrhalis, and Legionella sp. are becoming more important. The diagnosis of a specific etiologic agent is difficult in COPD and can be aided by obtaining specimens bronchoscopically. Directed therapy is optimal; however, empiric therapy is frequently unavoidable.