Objective To analyze the pathological changes of gastric mucosa in elderly patients with Helicobacter pylori(Hp) associated gastritis before and after eradication therapy, and to explore the importance of eradication treatment for these patients. Methods A total of 239 Hp associated gastritis cases, diagnosed with endoscopic biopsy, 13C-urea Breath Test and Hp stool antigen detection (HpSA) and had long-term follow-up data, were collected from April 1989 to June 2011. The pathological changes of gastric mucosa in these patients were observed before and after eradication therapy. Results Among 199 patients who underwent eradication therapy, the chronic inflammation was significantly alleviated in 179 patients; there were 64 patients who had active inflammation before treatment, and only 27 left after treatment. Among 66 patients who received incomplete eradication therapy, the chronic inflammation was significantly alleviated in 42 patients; there were 39 patients who had active inflammation before treatment, and only 22 left after treatment. Chronic inflammation and active inflammation were significantly alleviated in elderly patients receiving eradication therapy than in those receiving incomplete eradication therapy (P＜0.05). Conclusion Eradication therapy can significantly improve the histological chronic inflammation and active inflammation of gastric mucosa in elderly patients with Hp associated gastritis, and effectively reduce the incidence of chronic gastritis and alleviate the lesion.