Abstract
Dicroceliasis was studied parasitologically and pathologically in five wild Japanese serows. The worm found in the intrahepatic bile duct was identified to be the lancet fluke, Dicrocoelium dendriticum. The bile duct revealed severely hyperplastic epithelial cells accompanied by globule leucocytes. There was an infiltration of lymphocytes, plasma cells and eosinophils in the submucosa, with proliferation of granulation tissue in and around their walls. These findings coincided with those of Dicrocoelium infection in domestic animals.