INVESTIGATIONSto the reflux of bile as a factor in pancreatitis by techniques which involve direct cannulation of the pancreatic duct and the injection of bile and other substances into the gland are subject to numerous inconsistencies and criticisms.1,2To obviate some of these problems, methods have been described in the dog and the goat for the in vivo perfusion of the gland at pressures which are not artificial.2-5In these techniques all of the animal's bile is perfused through the gland. It has been stated5that this technique of in vivo perfusion allows for the mixing of bile salts and activated trypsin to occur within the pancreas.6Recently, however, the suggestion was advanced that bile is not only a relatively poor protease activator but may actually afford some protection in vivo against protease auto activation.2 In the present study a model was prepared in