In the aged, hiatal hernia should be recognized as it has developed; it develops progressively. Special attention should be given to the early stage of hiatal hernia from the genetic point of view. Like other organs in the aged, aging changes around a hiatus are inevitable; relaxing of esophageal diaphragmatic ligament and weakening of muscle power of diaphragmatic vertebral part move on with age. After all, valve structure at hiatus, Goubaroff's valve, is so weakened its function and in the stomach, "His angle" is so widened, that the stomach becomes wedge shaped against the hiatus. The more the pressure in the stomach increases, the larger the wedge shapes. Under these conditions, when the abdominal pressure rises by the acts of coughing or defecation, hiatus may be widened and the wedge may be pushed into the hiatus. There are no strong valve and or ligament enough to keep the wedge part of stomach in peritoneal cavity. In the stomach, the pressure of the expelling meal is equal to that of the widening wedge. On the other hand, in the peritoneal cavity, pressure produced by the act of defecation is equal to that of ejecting the wedge through hiatus. These are self-evident from the Pascal's principle. Hiatal hernia is produced under these conditions. We, therefore, should call the attention to the early genetic stage of hiatal hernia. In Japan, hiatal hernia has been recognized when it gets larger and fixes out of the peritoneal cavity. But in the early stage, it also must be noted as hiatal hernia.