Background Magnifying narrow-band imaging (NBI) endoscopy clearly visualizes superficial gastric mucosal patterns and capillary patterns. Objective To investigate gastric mucosal patterns by using magnifying NBI endoscopy and identify any relationship between those patterns and Helicobacter pylori –induced gastritis. Design Gastric mucosal patterns seen with magnifying NBI in uninvolved gastric corpus were divided into the following categories: normal—small, round pits with regular subepithelial capillary networks; type 1—slightly enlarged, round pits with unclear or irregular subepithelial capillary networks; type 2—obviously enlarged, oval or prolonged pits with increased density of irregular vessels; and type 3—well-demarcated oval or tubulovillous pits with clearly visible coiled or wavy vessels. Setting Department of Gastroenterology, Fujita Health University. Patients This study involved 106 participants undergoing upper endoscopy. Results H pylori infection–positive ratios of normal and types 1, 2, and 3 patterns were 7.5%, 92.9%, 94.5%, and 66.7%, respectively. Sensitivity and specificity for types 1 + 2 + 3 for detection of H pylori positivity and type 3 for detection of intestinal metaplasia were 95.2%, 82.2%, 73.3%, and 95.6%, respectively. Development of mucosal patterns from normal to types 1, 2, and 3 was correlated with all histological parameters ( P < .0001), lower pepsinogen I/II ratios ( P < .0001), and degree of endoscopic atrophy ( P < .0001). Sensitivity and specificity of type 3 for the prediction of severe histological atrophy was also better than those of serum pepsinogen level and standard endoscopy. Limitations Only 1 endoscopist performed endoscopic procedures, and interobserver agreement could not be assessed. Conclusions Magnifying NBI endoscopy is useful for predicting H pylori infection and the histological severity of gastritis and is valuable for predicting gastric atrophy in the entire stomach.