In spite of numerous experimental and clinical studies the pathogenesis of the disease resulting from pathological gastroesophageal reflux is yet unsettled. The importance of hiatus hernia has been questioned. The disturbed function of the lower esophageal sphincter does not always explain the occurrence of increased gastroesophageal reflux. there is no correlation between symptoms (pyrosis) and the typical esophageal mucosal changes which are best demonstrated by means of endoscopy. Guided biopsy is usually not necessary. Medical therapy consists in application of antacids, most effectively in combination with alginic acid. Further help can be expected from stimulation of the lower esophageal sphincter with metoclopramide and/or cholinergic drugs. Further measures are elevation of the head of the bed (30 degrees), reduction of body weight if necessary (to reduce intraabdominal pressure) and a high protein, low fat diet. Operative intervention (fundoplicatio) is rarely indicated, mostly in case of stricture.