We evaluated the effects of the use of nonsteroidal anti-inflammatory drugs (NSAIDs) on endoscopic and histological findings in patients with rheumatoid arthritis (RA) before and after the eradication of Helicobacter pylori infection. Helicobacter pylori (H. pylori) eradication using lansoprazole 30 mg, amoxicillin 750 mg, and clarithromycin 200 mg twice daily for 1 week was conducted in 44 patients (mean age: 56.5 years) with RA. Using the updated Sydney system, endoscopic and histological findings of the greater curvature of the antrum, the greater curvature of the upper corpus, and the lesser curvature of the lower corpus were compared before and after eradication, for a mean follow-up period of 3.5 months. Overall, H. pylori eradication was successful in 32 patients (72.7%). Of these 32 patients, 23 were NSAID users. In the successful eradication group, (1) there was no significant change on endoscopic findings, including gastric erythema and erosion in all three regions irrespective of NSAIDs use; (2) of 17 active ulcers before eradication in NSAIDs users, all healed except for one duodenal ulcer that persisted, where one patient newly developed a gastric ulcer, one developed erosive duodenitis, and two developed reflux esophagitis, all in NSAID users; (3) neutrophil infiltration and chronic inflammation were significantly improved in all three regions after H. pylori eradication irrespective of use of NSAIDs, while atrophic change and intestinal metaplasia did not change. In the eradication failure group; (1) there was no significant change on endoscopic and histological findings in the three regions; (2) two of three ulcers present before eradication on NSAID users persisted even after eradication, and no new cases of gastric ulcer or erosive duodenitis occurred. In conclusion, over a mean follow-up period of 3.5 months, use of NSAIDs in Japanese patients with RA did not impair the healing process of gastric and duodenal ulcers nor did it affect the endoscopic and histological improvements associated with H. pylori eradication.