Mesenteric lymphadenitis is by no means a new pathologic entity. Much has been written about in in recent years. However, as a clinical entity it is unknown or frequently forgotten by a large group of medical men as well as surgeons. I present this article in order to emphasize the fact that this disease occurs in everyday practice, and often just keeping it in mind allows one to explain an otherwise baffling array of symptoms. When one is on the lookout for this disease entity (if I may call it such), one may be rewarded by makin a correct diagnosis, the verification being made at the operating table. I am especially interested in mesenteric lymphadenitis from the point of view of: (1) diagnosis, which is often obscure; (2) etiology, which is still in doubt, and (3) treatment and prognosis. My experience and that of authors whose writings have been consulted