The unique characteristics of the everting catheter have suggested its application in the gastrointestinal system. The operation of the catheter promises to facilitate the catheterization of the pancreatobiliary ducts through the Papilla of Vater. An initial series of patients has undergone routine endoscopic retrograde cholangiopancreatography (ERCP) using the catheter for contrast infusion. An extensively modified catheter is passed through an appropriately positioned endoscope. The catheter tip is placed within the ampulla, and the element is everted. In basic ERCP, contrast medium is then injected for diagnostic procedures. Catheter modifications include an overall lengthening to approximately 200 cm, while eliminating any added length to the everting element beyond that required by the clinical procedure. This keeps frictional drag of the element to a minimum. Where kinking of the tip of the primary catheter in the elevator of the scope presents a problem, reinforcement of the tip or a change to PTFE materials is made. In addition, the catheter's ability to atraumatically negotiate small, tortuous ducts is being investigated for catheterization of remote pancreatic and cystic ducts for sampling of pure secretions, placement of biliary stents, and conveyance of CCD television cameras.