Diarrhoea may develop after any surgery of the digestive tract, but its frequency and characteristics vary according to the type of operation. After gastrectomy diarrhoea is rare, moderate and often cryptic. After all but hyperselective vagotomies it is more frequent and may even be disabling and difficult to control. Diarrhoea is observed and may even be disabling and difficult to control. Diarrhoea is observed mostly after intestinal surgery, but it may have nutritional repercussion only after small bowel resections, while its functional repercussions are observed after colonic resections. Diarrhoea depends on the length rather than on the location of the intestinal segment resected, hence the importance of a reserve intestinal tissue below the resection. Thus, jejunal resections are well tolerated, even they are extensive, whereas ileal resections, even short, often result in a diarrhoea which is particularly pronounced when the ilio-coecal region and adjacent colon have been removed. Finally, the presence of an artificial anus increases the intestinal loss and creates its own specific problems.