Many complications result from the migration of Ascaris lumbricoides into the biliary tree, most commonly thecommon bile duct. The findings on intravenous cholangiograph and adjunctive tomograph are diagnostic. The worm isseen as a longitudinal tubular translucent filling defect in the common bile duct or intrahepatic duct. We haveseen 17 patients who had a positive worm density on intravenous cholangiograph and tomography, and we haveextracted 1 to 22 Ascaris lumbricoides from the biliary tree of 13 patients by surgical maneuver. In the remaining4 patients antihelminthic medication has been given with subsequent disappearance of the worm density from thebiliary tree and improvement of the clinical symptoms and signs.