It is well known that heavy infestations of Opisthorchis felineus or Clonorchis sinensis produce cirrhosis of the liver in man and that a similar disease of the liver is produced in dogs and cats by multiple infection with any one of the following trematodes: Opisthorchis felineus, Metorchis truncatus, or Metorchis albidus. So far as we are aware, the pathogenicity of Opisthorchis pseudofelineus or Metorchis complexus has never been reported. Opisthorchis pseudofelineus was first described by Ward (1901) as a parasite from the liver of the domestic cat. Stiles and Hassall (1894) described Melorchis complexus and reported its occurrence in cats of New York, of Maryland and of the District of Columbia. They said nothing regarding the effect of this parasite on the host. Since the literature on the American liver fluke of the cat is chiefly concerned with morphology and systematics we are reporting the pathologic and other data on a cat infected with Opisthorchis pseudofelineus and Metorchis complexus.