Helicobacter pylori infection is a major cause of gastric mucosa-associated lymphoid tissue (MALT) lymphoma. Successful H. pylori eradication can induce a complete remission (CR); however, it takes a long time. In this case, the recurrence of gastric MALT lymphoma was observed by endoscopic and histologic findings during a 11-year follow-up and due to H. pylori reinfection twice. After the first successful eradication and achieving histologic CR, the patient was starting to work at a nursing home for older adults, where she frequently came in contact with their vomitus or feces. In the examinations 2 years later after the first successful eradication, endoscopic and histologic findings have demonstrated deterioration. Similar findings were continuously observed in the examinations 3 months later, and H. pylori reinfection was confirmed by the rapid urease test. After the second successful eradication, endoscopic and histologic CR of gastric MALT lymphoma was achieved. However, endoscopic and histologic findings have shown deterioration again 1 year later after the histologic CR and at 3.5 years later after the second successful eradication. H. pylori reinfection was confirmed by the repeated urea breath test, and the patient had received the third eradication treatment; and the patient had achieved successful eradication. In addition, proper hygiene practices were advised to avoid H. pylori reinfection. H. pylori reinfection is very rare in adults after successful eradication in developed countries. After successful eradication and proper hygiene practice, endoscopic and histologic CR has been maintained for 2 years up to the present.