In 66 male rats the hepatic duct was ligated close to the duodenum creating obstruction of both bile and pancreatic outflow, in another 60 rats the hepatic duct was ligated close to the duodenum, but the bile flow shunted from the proximal part of the hepatic duct to the duodenum, creating an isolated obstruction of the pancreatic outflow. In the first group, when the bile flow was stimulated with cholecystokinin (Cecekin®), reflux of bile into the pancreas occurred, resulting in a high frequency of hemorrhagic pancreatic necrosis. Reflux of bile did not occur and pancreatic necrosis was infrequent after secretin administration or in controls without stimulation, in the second group pancreatic necrosis occurred infrequently. From these experiments the following conclusions may be drawn: 1. In hepatic duct obstruction, when a common channel mechanism is present, reflux of bile into the pancreas occurs, if the bile flow is increased, 2. Reflux of bile causes severe damage to the pancreas, 3. Simple obstruction of the pancreatic outflow most often results in edematous pancreatitis and infrequently in pancreatic necrosis. The frequency of necrosis is not altered if the pancreatic secretion is stimulated with pancreozymin or secretin.