Neither sphincterotomy nor choledochoenterostomy has solved the problem presented by the patient who after cholecystectomy continues to have attacks of pain in the right upper quadrant which simulate biliary colic. In a paper on postcholecystectomy dyskinesia1I elaborated on the possible and also on some probable causes of such attacks of pain. From among the various possibilities definite evidence can be presented that one, namely inflammatory lesions in the biliary tract with associated inflammation of the sphincter of Oddi and stenosis, increases intraductal biliary pressure and produces attacks of pain. Many years ago McGowan, Butsch, and I2produced spasm of the sphincter of Oddi by injection of morphine or codeine. An increase in the intraductal biliary pressure resulted, and pain typical of biliary colic was produced. When 1/150 grain (0.4 mg.) of glyceryl trinitrate (nitroglycerin) was given sublingually or amyl nitrite was inhaled, intrabiliary pressure decreased immediately, and