In eight totally pancreatectomised patients the release of the relevant gut hormones was determined after a standard test meal. Plasma levels of pancreatic glucagon were not significantly different from zero in our series of pancreatectomised patients. Pancreatic polypeptide was undetectable. These findings imply the absence of a significant number of normally functioning alpha cells and pancreatic polypeptide cells in extrapancreatic sites in man. Consistent with the antrectomy, duodenectomy, and resection of the upper jejunum that are performed in conjunction with a total pancreatectomy the gastrin release was significantly impaired. In contrast there was a striking post-prandial rise in enteroglucagon probably induced by the rapid intestinal transit time often seen after partial gastrectomy. In contrast plasma motilin and GIP levels were normal. Pancreatectomised man thus presents an interesting model of total deficiency of endogenous insulin, pancreatic polypeptide, and pancreatic glucagon and, in addition, greatly diminished gastrin. The considerable derangement of metabolic and intestinal function that follows total pancreatectomy may, in part, be explained by this gross disturbance of the normal physiology of gut hormone.