To elucidate the role of bile and pancreatic juice in regulation of gut hormone secretion, an experimental study was performed creating models of biliary and pancreatic juice diversion in conscious dogs with reference to gastric acid and pancreatic exocrine secretions. The results were obtained as follows. 1) Diversion of bile from the duodenum to the jejunum, the ileum and urinary bladder (UB) did not affect the postprandial gastric acid and gastrin secretion, except slight suppression of gastric acid in model of bile diversion to the ileum and UB. 2) Postprandial GIP secretion was completely diminished and total-GLI secretion was significantly increased after bile diversion to the ileum and UB, whereas the jejunal diversion did not affect both GIP and total-GLI secretion. 3) A marked hypertrophy of pancreatic acinar cells was seen in conventional histopathological investigation and hyperfunction indicated by microelectroscopical findings was observed after bile diversion to UB with significant hypersecretion of CCK. 4) In the model of bile diversion to UB, hypersecretion of insulin was observed after intravenous glucose infusion test. 5) Diversion of pancreatic juice from the duodenum to the jejunum induced significant postprandial hypersecretion of gastric acid and hyposecretion of GIP.