Gastroscopy is the insertion of a thin tube into the stomach through the oral pharynx, and the images returned through the front section of the lens allow you to see the morphology and abnormal changes inside the esophagus, stomach and duodenum, even the smallest abnormalities. How often a gastroscopy is appropriate is a matter for the doctor to decide, depending on the condition. There are some people who should have regular gastroscopy, especially middle-aged people over 40 years old, it is better to have a gastroscopy screening. Especially for those who have genetic history of stomach tumor and live in areas with high incidence of stomach cancer, they can rule out stomach lesions at an early stage and can detect precancerous lesions. Gastroscopy follow-up for precancerous lesions can detect cancerous lesions at an early stage, and gastroscopic treatment can also be performed for precancerous lesions and early cancerous lesions. Because gastroscopy is the simplest and most accurate method of stomach examination, lesions in the stomach can be clearly seen, and if there are suspected lesions, biopsy can be done to determine benign or malignant. If it is only superficial gastritis and there are no obvious clinical symptoms, there is no need for treatment and the main focus is on maintenance, depending on the change in symptoms to decide when to review the gastroscopy. If it is atrophic gastritis, the interval of review will be decided according to the severity of atrophic gastritis, once a year for moderate atrophic gastritis and 5 years for mild atrophic gastritis. For those with gastric ulcers found on initial gastroscopy, gastroscopy should be repeated 4 to 8 weeks after treatment. For those with long-term chronic gastric disease, gastroscopy should be reviewed in a timely manner if the symptoms have changed significantly in the near future, the degree of aggravation, frequent attacks, and the failure of the original medication used.