I. Epigastric pain, either mild or severe, especially in patients with longer duration of disease and those over 50 years of age. II. Patients with unexplained loss of appetite and weight loss. III. Patients who vomit blood or have black stool. IV. Upper abdominal mass. V. Unfavorable swallowing or obstructive feeling when eating. VI. Those who have been diagnosed with atrophic gastritis. Seven, ulcer disease patients, gastroscopy can clearly understand the ulcer site, size, active bleeding, etc., but also to detect the presence of Helicobacter pylori in the stomach, to provide important materials for thorough treatment. After treatment, gastroscopy can be reviewed to understand the effect of treatment. Gastroscopy plus biopsy can determine benign and malignant lesions in patients with gastric and duodenal polyps. Gastroscopy can also be used for effective treatment, eliminating the need for surgery. Gastroscopy for patients after gastric surgery can detect possible cancer early. Patients with acid reflux and heartburn can understand the presence of esophagitis, its scope, nature and severity through gastroscopy. XI. Metastatic cancer is found in other parts of the body and the primary lesion needs to be found. Foreign objects (such as pins, buttons, rings, steel needles, keys, date pits, fish spines, necklaces) swallowed can be removed through gastroscopy and supporting tools without surgery. People with family history of cancer, or people in areas with high incidence of stomach and esophageal cancer should have routine gastroscopic examination.