Nine cases of cystic and cylindric bile duct dilatation are discussed. They were treated at the Children's Surgical Hospital of the University of Munich from 1970 to 1984. The patients' mean age was 4.2 years. Upper abdominal sonography in combination with hepatobiliary functional scintigraphy or computer tomography has been proven the best diagnostic procedure. The operating procedure of choice is a total cyst excision followed by an end-to-end anastomosis or a hepatojejunostomy according to the Roux-Y-technique. There were no immediate postoperative complications such as cholangitis. In one case we found a stenosis of the anastomosis after primary hepatocholedochostomy.