Abstract Background The grade of gastric mucosa atrophy caused by Helicobacter pylori ( H. pylori ) infection is closely associated with the risk of gastric cancer, especially of the intestinal type. Interobserver and intraobserver agreement for endoscopic gastric mucosa atrophy in subjects with H. pylori -uninfected, currently infected and past infected was investigated. Methods Endoscopic images of 91 patients, 34 images per patient, were assessed. The assessors were 4 endoscopist groups: Japanese and Vietnamese experienced (≥7, ≤ 15 year experience with endoscopy) and Japanese and Vietnamese beginner (≤ 3 year experience) groups. Each group comprised 3 endoscopists. The grades of atrophy were classified as 3: none to mild (C-0 and C-1), moderate (C-2 and C-3), and severe (O-1, O-2, and O-3) using the Kimura-Takemoto Classification. After a period of 2 weeks, images of all patients were reevaluated by the investigators. Interobserver and intraobserver agreement was calculated by kappa statistics. Results The kappa values for the interobserver agreement in the groups of Japanese and Vietnamese experienced, and Japanese and Vietnamese beginner were 0.474, 0.408, 0.291, and 0.373, respectively. The kappa value of intraobsever agreement in the Japanese and Vietnamese experienced endoscoists ranged from 0.585 to 0.871. On the other hand, the value in the beginner endoscopists ranged wider than that in experienced endoscopists, from 0.264 to 0.866. Conclusions Our results indicated that, although intraobserver agreement for gastric mucosa atrophy was good to excellent, interobserver agreement was moderate in experienced endoscopists. This suggests that better guidelines and firm criteria may be needed to properly diagnose and grade gastric atrophy.