Gastric cancer(GC) develops as a result of inflammationassociated carcinogenesis due to Helicobacter pylori(H. pylori) infection and subsequent defects in genetic/epigenetic events. Although the indication for eradication therapy has become widespread, clinical studies have revealed its limited effects in decreasing the incidence of GC. Moreover, research on biopsy specimens obtained by conventional endoscopy has demonstrated the feasibility of the restoration of some genetic/epigenetic alterations in the gastric mucosa. Practically, the number of sporadic cases of primary/metachronous GC that emerge after successful eradication has increased, while on-going guidelines recommend eradication therapy for patients with chronic gastritis and those with background mucosa after endoscopic resection for GC. Accordingly, regular surveillance of numerous individuals who have received eradication therapy is recommended despite the lack of biomarkers. Recently, the focus has been on functional reversibility after successful eradication as another cue to elucidate the mechanisms of restoration as well as those of carcinogenesis in the gastric mucosa after H. pylori eradication. We demonstrated that Congo-red chromoendoscopy enabled the identification of the multifocal distribution of functionally irreversible mucosa compared with that of restored mucosa after successful eradication in individuals at extremely high risk for GC. Further research that uses functional imaging may provide new insights into the mechanisms of regeneration and carcinogenesis in the gastric mucosa post-eradication and may allow for the development of useful biomarkers. Gastric cancer (GC) develops as a result of inflammationassociated carcinogenesis due to Helicobacter pylori (H. pylori) infection and subsequent defects in genetic / epigenetic events. Although clinical studies have revealed its limited effects in decreasing the incidence of GC. Moreover, research on biopsy specimens obtained by conventional endoscopy has demonstrated the feasibility of the restoration of some genetic / epigenetic alterations in the gastric mucosa. Practically, the number of sporadic cases of primary / metachronous GC that emerge after successful eradication has increased, while on-going guidelines recommend eradication therapy for patients with chronic gastritis and those with chronic mucosa after endoscopic resection for GC. focus has been on functional re versibility after successful eradication as another cue to elucidate the mechanisms of restoration as well as those of carcinogenesis in the gastric mucosa after H. pylori eradication. We demonstrated that the identification of the multifocal distribution of functionally irreversible mucosa compared with that of restored mucosa after successful eradication in individuals at extremely high risk for GC. Further research that uses functional imaging may provide new insights into the mechanisms of regeneration and carcinogenesis in the gastric mucosa post-eradication and may allow for the development of useful biomarkers.