A Double-crested Cormorant, Phalacrocorax auritus, was found infected with the opisthorchiid trematode, Amphimerus elongatus. The liver was badly riddled with a massive infection of thousands of these parasites. Histologically, trematodes were found in the bile ducts of almost all the lobules of the liver. These were completely occluded and there was hyperplasia or complete desquamation of the epithelium of the duct walls. In areas which contained numerous parasites there was extensive fibrosis. In lobules which were free of the parasites the hepatic cells exhibited cloudy swelling, their nuclei were karyolytic in areas adjacent to fibrosis, and there was a considerable increase in the periportal tissue. A localized inflammatory response was noted with lymphocytes and eosinophils as the main cellular components. This is the first record of A. elongatus from the Double-crested Cormorant.