In 44 patients who had been operated upon for benign obstruction of the biliary tract and had undergone sphincteroplasty or choledochoduodenostomy seven to 12 years previously, patency of the new stoma was evaluated. Dynamic studies of bile flow were done by radioisotopic cholangiography, using 99mTc-pyridoxal-phenylalanine as an hepatobiliary imaging agent. Both surgical procedures seem to give equal results in the long term follow-up study regarding the patency of a new stoma. In view of the fact that choledochoduodenostomy involves less morbidity and mortality postoperatively, than does sphincteroplasty, the former is preferred unless a stone is impacted into the ampulla of Vater or if the common bile duct is less than 2 centimeters in diameter in instances of stricture.