Many complications result from the migration of Ascaris lumbricoides into the biliary tree, most commonly bile duct. The findings on intravenous cholangiograph and adjunctive tomograph are diagnostic. The worm is seen as a longitudinal tubular translucent filling defect in the common bile duct or intrahepatic duct. We have seen 17 patients who had a postive worm density on intravenous cholangiograph and tomography, and we have extracted 1 to 22 Ascaris lumbricoides from the biliary tree of 13 patients by surgical maneuver. In the remaining 4 patients antihelminthic medication has been given, with subsequent disappearance of the worm density from the biliary tree and improvment of the clinical symptoms and signs.