I first discovered that oral odor was associated with H. pylori infection about 7-8 years ago. Once a male patient in his fifties came for a gastroscopy because of recurrent epigastric pain. During the examination, it was found that the patient had a large gastric stone in his stomach and a large ulcer had been worn out by the stone in the corner of his stomach. However, the patient was also found to have H. pylori infection during the gastroscopy, so I treated the patient with antibiotics for H. pylori infection along with the stomach stones and ulcer. Two months later, the patient came for a follow-up examination and the ulcer had completely healed, and the patient happily told me that not only was his stomach disease cured by me, but his bad breath, which had been bothering him for years, had also disappeared.