From 1975 to 1989 operations were carried out in the clinic by various methods on 30 children with cysts of the common bile duct. Hepaticoor choledochojejunostomy after Roux is the operation of choice in cysts of the choledochus. However, recurrent cholangitis caused by jejunobiliary reflux was encountered in some patients in the postoperative period. The accumulated clinical experience has also shown that the Roux type operation does not guarantee a successful functional result. To prevent reflux of the intestinal contents into the biliary tract after Roux's anastomosis, the authors used an antireflux valve on the excluded loop of the jejunum. Experimental study was undertaken of the theoretically substantiated antireflux valve on an excluded loop of the type of a "nonspilling inkpot" with a shortened loop. The creation of an antireflux valve in the form of an invaginated segment prevents jejunobiliary reflux and therefore provides the possibility for reducing significantly the length of the excluded loop in Roux's biliodigestive anastomoses. The obtained positive results confirm the rationality of this construction which does not need additional time for the operation. Since 1987 four children have been operated on by this method in the clinic. The length of the excluded loop was reduced from 30 to 15 cm. Postoperative complications linked with reflux into the biliary system were not encountered.