The Parasitological investigation on the encysted metacercariae in brackish water fish, Tribolodon taczanowskii Steindachner, in the downstream of Hyungsan river which is located in Kyungpook province of Korea, were carried out, and the following results were obtained.

1) Metacercariae of Metagonimus species were found in seventy five fishes (40.5%) out of 185 examined.

2) Parasitic frequencies of the encysted matacercaria of Metagonimus species in Tribolodon taczanowskii were 23.2% (43 out of 185) in the scale, 7.0% (13 out of 185) in the gill, and 10.3% (19 out of 185) in the flesh.

3) The number of the metacercaria in the scale, gill and flesh were fewer than that of the others.

4) The worms were identified as Metagonimus yokogawai Katsurada, 1912 by morphological studies on the adults and eggs, and compared with prereported Metagonimus species.