Investigators found that the degree and the duration of aceto-whitening differed between gastric intestinal metaplasia(GIM) and the surrounding normal mucosa: the area of GIM showed a severe degree of aceto whiteness and the whitening continued longer than the surrounding normal mucosa, which investigators called "severe whitening" and "delayed fading", and investigators realized that GIM could possibly be diagnosed by using these differences.The aim of this prospective study was to investigate the efficacy of "severe whitening" and "delayed fading" for diagnosing GIM.

Inclusion Criteria:

• long-lasting upper gastrointestinal symptoms (>15 years)
• atrophic gastritis or GIM identified at surveillance endoscopy

Exclusion Criteria:

• presence of advanced adenocarcinoma in the stomach
• presence of acute gastrointestinal bleeding
• presence of coagulopathy, uncontrolled impaired renal or liver disease
• presence of pregnancy or lactation
• presence of allergy to acetic acid
• age younger than 18 years or older than 80 years
• inability to provide written informed consent.