Nausea, vomiting, and abdominal pain are common symptoms that suggest many diagnoses. The patient's symptoms may be related to an anatomical defect such as a peptic ulcer or a mechanical small bowel obstruction. However, no anatomical abnormality may be identified despite radiological, endoscopic, or laboratory studies. The cause of the patient's symptoms may have significant impact on the patient's quality of life (nonulcer dyspepsia) and life span (intestinal pseudo-obstruction). Abnormal antroduodenal motility may be the underlying cause of the patient's symptoms. Normally, coordinated phasic contractions in the stomach and small intestine maintain digestion and absorption of food. A prolonged set of phasic contractions (phase 3 of the migrating complex) begins in the stomach and propagates down the small intestine to excrete nondigestible foods, bacteria, and dead cells. Any disturbance in the normal motility pattern can lead to maldigestion and symptoms of upper intestinal dysfunction. Objective tests of motility disturbances in the stomach and small intestine include measurement of gastric emptying, intestinal transit, contractions of the stomach and duodenum, and electrogastrography. Abnormal antroduodenal motility may be secondary to an abnormality in the smooth muscle (myopathy) or the nerves in controlling smooth muscle contractions (neuropathy). Antroduodenal motility measurements may help identify a partial small bowel obstruction, the cause of small intestinal overgrowth, and the cause of chronic abdominal visceral pain. Motility studies may suggest useful drugs for correcting the underlying pathophysiology and relieving symptoms.