Upper gastrointestinal endoscopy, like many other diagnostic and therapeutic procedures, may be associated with discomfort. Although upper endoscopy is usually of shorter duration and better tolerated by patients, most trials investigating the influence of analgesia and sedation have been performed on patients undergoing this procedure. Some patients may tolerate colonoscopy without sedation, but various techniques are used to limit discomfort and pain. Selection and dosing of sedatives depends on the patient's emotional state, the intensity of pain during examination, foreseeable technical difficulties, the endoscopist's experience, the presence or absence of anesthesia personnel, and hospital-specific procedures.