Although epidemiological studies strongly suggest an association between Helicobacter pylori infection and gastric carcinogenesis via a multistage process, a causal link between them has not been demonstrated. We evaluated the endoscopic and histological changes of gastric adenoma, which is considered a premalignant condition, after eradication of H. pylori. Thirty-five H. pylori-infected patients with gastric adenoma were treated with triple therapy (lansoprazole 30mg/day, clarithromycin 400mg/day, and amoxicillin 1500 mg/day) for 1 week. Of these 35 patients, 30 (86%) exhibited no H. pylori by culture or histology after the therapy. Of the 30 gastric adenomas, 7 decreased in size endoscopically; three gastric adenomas especially showed apparent remission, although histological cure in these three patients was not apparent. Our results suggest that removal of H. pylori infection may only mask a gastric adenoma endoscopically owing to the change around the gastric mucosa.