The Parasitological investigation on the encysted metacercariae in brackish water fish, Tribolodon taczanowskii, in the downstream of Hyungsan river which is located in Kyungpook Province of Korea, were carried out serially and the following results were obtained. Metacercariae of Pseudexorchis major were found in six fishes(15.8 per cent ) out of 38 examined. Parasitic frequencies of the encysted metacercaria of Psedexorchis major in Tribolodon taczanowskii were 15.8 per cent (6 out of 38) in the scale, 10.5 per cent (4 out of 38) in the fin, 13.2 per cent (5 out of 38) in the gill, 10.5 per cent (4 out of 38) in the oral cavity and 7.9 per cent (3 out of 38) in the flesh. The worms were identified as Pseudexorchis major (Hasegawa, 1935) Yamaguti, 1938 by morphological studies on the metacercariae, excysted metacercariae, adults and eggs, and compared with prereported Pseudexorchis species.
