Aspiration pneumonia in patients who received enteral feeding via a nasogastric tube may result from retrograde colonization from the stomach, and this may be more likely when the gastroesophageal reflux is severe and the gastric pH is relative high. We investigated 11 elderly patients fed via nasogastric tube with suspected recurrent aspiration pneumonia by means of esophageal scintigraphy, 24-h pH monitoring, gastric pH and concentrations of gram-negative bacilli in gastric aspirates. The grade of respiratory tract infection (RTI) was evaluated by the frequency of episodes of fever with respiratory symptoms. The correlation between the grade of RTI and reflux index by scintigraphy was statistically significant (p < 0.05), but the correlation between the grade of RTI and reflux rate by 24-h pH monitoring was not statistically significant. Although the correlation between gastric pH and log (base 10) concentration of gram-negative bacilli/ml of gastric aspirates was statistically significant (p < 0.001), the correlation between the grade of RTI and gastric pH was not statistically significant. Scintigraphy was superior for evaluation of gastroesophageal reflux resulting in aspiration pneumonia in the tube-fed elderly patients.