The general aim of the thesis was to contribute to a more evidenced based framework in the surgical treatment of diseases in the gastroesophageal junction (GEJ), by comparing outcome, measured by complication and survival rates, and evaluate different reconstructions regarding long-term symptoms and quality of life (QoL). The GEJ is a poorly defined anatomic area that represents the lower part of the esophagus and its’ junction to the proximal stomach.Diseases in this area cause symptoms that affect negatively the QoL for the patients and often interfere with the ability to eat and drink. The surgical treatments not only aim at eliminating the patient’s symptoms but also to cure her/his sometimes life-threatening condition. In Paper I we compared two different antireflux procedures in the treatment of gastroesophageal reflux disease (GERD). Many patients do not respond to acid suppressor medication making the need of an antireflux procedure with good long-term functional results important. Epiphrenic diverticula are rare but can cause life-threatening conditions. In Paper II we studied the treatment of symptomatic epiphrenic diverticula, and evaluated the outcome after an antireflux procedure had been added to the myotomy, and studied the long-term effect after surgery both regarding symptoms relief and QoL. The incidence of adenocarcinoma (AC) in the GEJ increases rapidly in the Western world. In Paper III we compared the extensive and less used extended gastrectomy with long Roux-en-Y loop with the more commonly used esophagectomy with gastric tube in the treatment of AC in the GEJ. In Paper IV, we validated the paracetamol absorption test for measuring emptying from the gastric tube and compared it to gold standard, scintigraphy. In Paper V, we evaluated if there is a place for redoing reconstruction of the esophagus when the primary reconstruction fails. In conclusion, reconstruction for diseases in the GEJ can, both for benign and malignant diseases, be performed with a low postoperative morbidity and mortality, and with good long-term results. In the treatment of GERD, both a total and an anterior 120° fundoplication result in good long-term QoL. Treatment of epiphrenic diverticula should include a myotomy extended through the LES and an antireflux procedure, although the long-term QoL will remain impaired despite good postoperative regression of the primary symptoms. For AC in the GEJ, the extended gastrectomy can be used safely as a complement to esophagectomy and with good long term functional results and QoL. The paracetamol absorption test may be used as an alternative to scintigraphy for identifying delayed emptying from the gastric tube. In case of failure of the primary reconstruction, the patient should be offered another attempt, since it is possible to achieve an equally good outcome after a redo-reconstruction as after a primary reconstruction