Aim Community‐acquired pneumonia (CAP) is presumed to be bacterial in origin and empirical antibiotics are almost always given on admission. However, early detection of viral infection is also very important for hospital infection control and timely use of antiviral agents. The present study aimed to compare patients with viral and bacterial pneumonia, and identify independent predictors of viral pneumonia. Methods A prospective cohort study was carried out in a tertiary teaching hospital in a 1‐year period. Older patients (aged ≥65 years) were recruited if they were admitted for CAP confirmed by chest radiographs. Results A cohort of 488 patients was analyzed. Infective causes were found in 137 (28.1%) patients. Bacterial, viral and mixed infections were detected in 86 (17.6%), 41 (8.4%) and 10 (2.0%) patients, respectively. Bacteriology was established mostly by sputum culture and virology by nasopharyngeal aspirate (NPA) viral culture. The commonest bacterial isolates were Haemophilus influenzae (31), Pseudomonas aeruginosa (15), Mycobacterium tuberculosis (14), Klebsiella spp. (9) and Streptococcus pneumoniae (6). Influenza A virus (28, 8 were pandemic 2009 A/H1N1 subtype) and respiratory syncytial virus (16) were the most frequent viral causes. Independent predictors of viral pneumonia included nursing home residence (RR 3.056, P = 0.009) and absence of leukocytosis (RR 0.425, P = 0.026). Conclusions All nursing home residents hospitalized for CAP should undergo NPA viral testing because of infection control, early antiviral treatment and discharge planning. We suggest that empirical antiviral agents might be considered for nursing home residents hospitalized for CAP if outbreaks of influenza‐like illness are reported in nursing homes. Geriatr Gerontol Int 2013; ●●: ●●–●●.