To investigate the clinicopathological features of the patients testing negative for high titer serum anti- ( ) antibody. The antibody titers were measured using antigens derived from Japanese individuals. C-urea breath test-positive individuals were defined as having infection. We investigated the demographic characteristics, laboratory data, endoscopic findings including Kyoto classification of gastritis, and histology in negative-high titer patients without eradication therapy. Kyoto classification consisted of scores for gastric atrophy, intestinal metaplasia, enlarged folds, nodularity, and redness. Of the 136 subjects enrolled, 23 (17%) had infection. Kyoto classification had an excellent area under the receiver operating characteristics curve (0.886, 95% confidence interval: 0.803-0.968, = 3.7 × 10 ) for predicting infection with a cut-off value of 2. Further, Kyoto classification, density, and neutrophil activity had high accuracies (89.7%, 96.3%, and 94.1%, respectively). Kyoto classification was independent of the demographic and laboratory parameters in multivariate analysis. Endoscopic Kyoto classification of gastritis is a useful predictor of infection in negative-high titer antibody patients.