The three main symptoms of esophageal disease or disorder are dysphagia, chest pain, and heartburn. Dysphagia in achalasia is mainly due to a non-relaxing lower esophageal sphincter (LES). The mechanism of dysphagia in diffuse esophageal spasm and related motor disorders is related to a combination of several factors including incomplete LES relaxation, failed or weak peristalsis (pressure less than 30 mmHg in the distal esophagus, and orad positive pressure gradient). Meal manometry and balloon distention may prove to be useful provocation tests. Chest pain of esophageal origin may be due to gastroesophageal reflux and esophageal motility disorders; it may also be a manifestation of an irritable esophagus, in which the esophagus is hypersensitive to various stimuli (chemical, mechanical, ischemic). Esophageal provocation tests may suggest the esophageal origin of the pain but do not give information on the nature of the esophageal disorder. Twenty-four-hour pH and pressure measurements may, however, yield this information. Heartburn and acid regurgitations are the most typical symptoms of gastroesophageal reflux. Transient relaxations of the LES are considered to be an important contributory mechanism of reflux. Absent basal LES pressure is another mechanism, which accounts for about one-fourth of the reflux episodes in patients with severe reflux esophagitis. During long-lasting inappropriate relaxations, swallows often produce deglutitive contraction waves that die out in the upper esophagus, suggesting that reflux often occurs during periods of inhibition of both LES tone and peristaltic esophageal activity.