Objective　To investigate the mechanism by which Helicobacter pylori induces gastric mucosal damage. Method　The gastric epithelial apoptotic index （AI） of normal mucosa and H. pylori positive gastritis before and after anti-H. pylori treatment was studied using terminal transferase-mediated dUTP nick end labeling （TUNEL）. Results　The mean of AI was 7.1±1.6 in 31 patients with H. pylori positive gastritis and was significantly higher than 1.3±0.6 in 16 normal controls （P＜0.001）. After the eradication of H. pylori AI fell significantly to the normal level （P＜0.001）. In persisting H. pylori positive gastritis, the AI showed no significant change. There was no correlation between the AI and the severity of gastritis. Conclusion H. pylori infection could induce gastric epithelial apoptosis, which may be an important mechanism in the pathogenesis of gastric mucosal damage in H. pylori.