Hyperperistalsis during upper gastrointestinal endoscopy may interfere with accurate diagnosis and lead to failure to detect microcarcinoma. Therefore it frequently necessitates the use of antispasmodic agents, but these drugs have side effects. In this review, the author notes note the effectiveness of peppermint oil administration to the gastric mucosa resulted in inhibiting the gastric peristalsis in Japanese individuals undergoing upper gastrointestinal endoscopy.