To determine whether elderly patients have an increased incidence of postoperative pneumonia and/or an increased mortality, we conducted a retrospective study of 4,380 patients who underwent thoracic, abdominal or neurosurgery under general anesthesia. Thirty of these patients developed postoperative pneumonia (incidence, 0.68%). The elderly patients aged 65 years or older who underwent thoracic surgery had the highest incidence of pneumonia. Nine of the 30 patients with pneumonia died (mortality, 30%). Elderly patients did not show a higher mortality than the younger patients. The extent of pulmonary infiltrates on chest roentgenogram and the serum bilirubin level, both of which were determined at the onset of pneumonia, independently had a significant association with mortality. Our study suggests that advanced age is a risk factor for postoperative pneumonia in patients who undergo thoracic surgery.