To the surgeon, the importance of duodeno-gastro-esophageal reflux is related firstly to the injurious effects it has on the mucosa of the stomach and the esophagus, and secondly to the underlying pathophysiology causing the regulation of duodenal contents into the stomach and subsequently into the esophagus. Normally, the reflux of duodenal contents into the stomach rarely causes symptoms and consequently is usually not a primary disease. The symptoms develop after operations that distort or remove the pylorus. Consequently, in most situations the disease is iatrogenic in etiology. In contrast, the reflux of duodenal and gastric contents into the esophagus occurs very commonly as a primary disease entity. In such patients, a dysfunctional lower esophageal sphincter is the cause of the increased esophageal exposure and is of key importance to the surgeon. Surgery is the only treatment modality, which is able to specifically address and correct a structurally defective and dysfunctional lower esophageal sphincter. For patients with excessive duodenal reflux into the stomach, surgical diversion of the offending refluxate by means of a Roux-en-Y procedure is the only truly effective modality of treatment.