The clinical profiles and pathogenesis of reflux esophagitis in elderly patients are not fully understood. To clarify the pathogenetic mechanisms of reflux esophagitis of the elderly, clinical profiles and the results of 24-h pH monitoring study were compared between 12 non-elderly (< 65 years) and 24 elderly (65≦years) cases with esophagitis. Female patients were more frequently observed in elderly than in non-elderly. Body mass index, presence of hiatus hernia, kyphosis, habitual smoking and resistance to the treatment of H2-receptor antagonists of the elderly patients were similar to those of the nonelderly patients. In addition, there was no significant difference in all parameters (gastro-esophageal reflux, percent time of pH < 4.0 of esophagus, esophageal and gastric pH and esophageal acid clearance time) obtained by 24-h pH monitoring study between elderly and non-elderly patients. In summary, the pathogenesis of reflux esophagitis in the elderly is similar to that in the non-elderly.