Normal physiologic pressures in the pancreatic and common bile ducts have proved difficult to measure. Various methods of recording pressures have been described,* but all the methods have involved either producing a fistula or occlusion of the major duct by the recording cannula. The preliminary objective of the present investigation was to develop a method whereby the pressures could be recorded without producing a fistula or occluding the ducts and without interfering with any sphincteral mechanism which might control the flow of bile or pancreatic juice from the ducts into the duodenum. A method was developed which satisfactorily met these criteria, a method by which simultaneous recordings of pressures in the pancreatic duct, in the common bile duct, and in the duodenal lumen could be made from cannulae placed in these organs. The experiments were carried out on trained dogs which had fully recovered from the operative procedures of placing