In a sliding hiatus hernia, the esophagogastric junction is above the diaphragm. It is called a sliding hernia because anatomically it resembles a sliding inguinal hernia and not because of an upward and downward motion through the esophageal hiatus. Symptoms may arise from the hernia because it becomes distended or bleeds; much more commonly the hernia is said to produce gastroesophageal reflux with its secondary complications. However, certain clinical and manometric data suggest that the hernia may be an associated and inconsequential finding so that reflux probably depends upon the lower esophageal sphincter efficiency rather than the presence of a hernia. The role of the phrenoesophageal ligament and its actual existence are still debated. A lower esophageal ring cannot be assumed to indicate that a hernia is present; more than likely the ring marks the upper limits of the lower esophageal sphincter. Although inadequate data are available concerning the natural history of the symptom complex attributed to a hernia, in a large proportion of such patients, symptoms become mild or may disappear on so-called medical therapy. Consequently, the results of surgical therapy need to be cautiously evaluated.