The purpose of this article is to consider first the mesenteric lymph nodes in that part of their function which has to do with infection; next to report the data on the cases of disease of the mesenteric lymph nodes that were found in the records from one hospital from 1914 to Aug. 1, 1936, and third, to point out that a broader interpretation of the mesenteric lymph nodes is definitely indicated regarding their place in diagnosis and treatment. The fact that 123 unselected cases have been studied and analyzed for comparison may be of interest to other clinicians who appreciate the importance of whatever rôle it is that the mesenteric lymph nodes play in abdominal or in general disease. Investigators have tried to impress clinicians with the importance of proper and timely treatment of abdominal disease. Practitioners having the responsibility of handling children have been particularly warned not to