IN 1906 a monograph was published by Moynihan classifying the various types of retroperitoneal fossz in which a hernia has been found, and giving the literature u p t o that date. I n 1915 the present writer took advantage of a case occurring in his practice to report on the recorded cases from 1906 t o that time. Another patient suffering from this rare and interesting condition has lately been under his care, and as a further period of nine years has elapsed and some new types of hernia have been described, i t seems a suitable opportunity t o bring the Iiterature up t o date arid t o summarize it.H e will not on this occasion describe cases which have been unsuspected during life and discovered post mortein, but confine himself t o those in which there were symptoms and, usually, a n operation.Case.-C. B., male, age 20, admitted to the Bristol Royal Infirmary in August, 1923, suffering from intestinal obstruction. The history given was that he had been subject to numerous attacks of the same type all his life, having had forty or fifty in all. They usually lasted about two or three days, and then passed off. In each attack there was abdominal pain, vomiting, stoppage of the bowels, and some distention. Nothing special was to be made out on examination of the abdomen, except some general distention of the small-gut type. I waited a day or two to see if it would pass off, but as it did not, I operated on Aug. 18. and found that many feet of jejunum were herniated into a typical left paraduodenal fossa of Landzert, showing the inferior mesenteric vein in the free border of the sac. The coils of gut were withdrawn, but as the condition was bad, and the gut very distended, no attempt was made at that time t o close the mouth of the sac. There was some suppuration of the abdominal wall, but the patient recovered, and had no further attacks. On Sept. 29, 1923, I operated again to close the sac, but found that the mild adhesive type of peritonitis which accompanied the suppuration of the abdominal wall had made a recurrence impossible by adhesions of the jejunum and plastic closure of the mouth of the sac.