We performed an observational analysis of prospectively collected data on 1,474 adult patients who were hospitalized for community-acquired pneumonia; 1,169 patients were under 80 years of age and 305 (21%) patients were over 80 years ("very elderly"). Mean patient ages were 60 years in the former group and 85 years in the latter group. Severely immunosuppressed patients and nursing-home residents were not included. Comorbidities significantly associated with older age were chronic obstructive pulmonary disease, chronic heart disease, and dementia. The most common causative organism was Streptococcus pneumoniae (23% in both groups). Aspiration pneumonia was more frequent in the very elderly (5% in younger patients versus 10% in the very elderly); Legionella pneumophila (8% in younger patients versus 1% in the very elderly) and atypical agents (7% in younger patients versus 1% in the very elderly) were rarely recorded in the very elderly. While very elderly patients complained less frequently of pleuritic chest pain, headache, and myalgias, they were more likely to have absence of fever and altered mental status on admission. No significant differences were observed between groups as regards incidence of classic bacterial pneumonia syndrome (60% versus 59%) in 343 patients with pneumococcal pneumonia. The development of inhospital complications (26% in younger versus 32% in very elderly patients) as well as early mortality (2% in younger versus 7% in very elderly patients) and overall mortality (6% in younger versus 15% very elderly patients) were significantly higher in very elderly patients. Acute respiratory failure and shock/multiorgan failure were the most frequent causes of death, especially of early mortality. Factors independently associated with 30-day mortality in the very elderly were altered mental status on admission (odds ratio, 3.69), shock (odds ratio, 10.69), respiratory failure (odds ratio, 3.50), renal insufficiency (odds ratio, 5.83), and Gram-negative pneumonia (odds ratio, 20.27).