On August 5, 1937, during the examination of perch obtained from the commercial fisheries in Cheboygan, Michigan, the intestine of one fish was found to contain four mature nematodes, apparently belonging to the genus Rhabdochona Railliet (1916) of the family Thelaziidae Railliet (1916). The fish were caught just north of Big Stone Bay in the Straits of Mackinaw in Michigan. In the examination of 136 perch from this locality and of 519 perch from the inland lakes of northern Michigan during the summers of 1936 and 1937, no other examples of this genus were collected. This nematode appears to be a new species and for it the name Rhabdochona ovifilamenta is proposed.