Two American goldeneye ducks, Bucephala clangula americana (Anatidae), collected from the Galveston, Texas, U.S.A., area were infected with 5 (2 in 1 duck and 3 in the second) Ophthalmophagus bucephali n. sp. (Cyclocoelidae). Two additional specimens of this species, also collected from the American goldeneye from Hastings, Minnesota, U.S.A., were found in the holdings of the H. W. Manter Laboratory of Parasitology, University of Nebraska, Lincoln, U.S.A. The new species can be distinguished from all other species in the genus by having the ovary contiguous with the posterior testis and by having the prepharynx longer than the esophagus (approximately twice as long). Ophthalmophagus bucephali n. sp. can be distinguished from all other species except for Ophthalmophagus massinoi by having uterine loops that do not invade the postovarian space and from all species except Ophthalmophagus singularis by having the ovary contiguous with the posterior confluence of the ceca (cyclocoel). A checklist of parasites previously reported from B. clangula is also provided.