Diseases and malformations of the oesophagus have hitherto been a neglected field in paediatrics. During recent years this attitude has been altered, because the progress of thoracic surgery has made operations on the oesophagus a much safer procedure and has thus increased the possibility of treating surgically oesophageal lesions in children. Among the diseases and malformations which have become the object of renewed interest is congenital hiatal hernia coexisting with a shortening of the oesophagus, which Scandinavian and French workers are accustomed to call " brachyoesophagus." PREVioUS REPORTS A review of about 70 cases reported up to 1947 can be found in a paper published by one of us (Thomsen, 1949). In addition to several single cases, two large series were published in 1948, one from England and one from America, Allison reporting seven cases and'Olsen and Harrington eight among children. Considering that the condition has been known for almost 30 years, the number of published cases, about 100, is not impressive, and, judging by the literature, short oesophagus would appear to be rare among children. It would seem, however, that the literature does not convey the proper impression, since we have been able to collect 24 cases diagnosed within the last decade, 14 of them since 1947. AETIOLOGY As stated in the previous paper (Wamberg, 1947) some disagreement has existed as to the aetiology. According to Bund a persistence of the right pneumato-enteric recess produces a hernia in which the stomach forms the hernial contents. Tondorff, on the other hand, claims that the caudal shift of the diaphragm and abdominal contents, which normally takes place in the fourth to fifth foetal week, is disturbed so that the longitudinal growth of the oesophagus ceases and a major or minor portion of the stomach remains in the thoracic cavity, whereas the diaphragm, completing its caudal movement, envelops the thoracic stomach in a thin layer of connective tissue. Recent papers, particularly from England (Allison, 1948), have shown that none of these theories can be accepted. The fact that short oesophagus and peptic ulcer of the oesophagus are met with in a comparatively large number of subjects over 50 years of age with no history of dyspeptic symptoms militates against the idea of a congenital defect. In 1926 Akerlund described a form of hiatal hernia, occurring particularly among elderly individuals, in which the hernial