In an attempt to clarify the epidemiological feature of distomiasis in Tongjin riverside area, the prevalence of distomiasis in the residents and infection rates of the metacercariae in fresh-water fishes were investigated at the upper, middle and lower reaches of the river from January to April, 1984. The results obtained were summarized as follows: 1. Out of a total of 931 fresh-water fishes which composed of 33 different species, 611 fishes(65.6%) of 31 species were found positive with digenetic trematode metacercariae of 16 different species, and there were some differences in infection rates of the metacercariae among the fishes in the 3 parts of the river; 53.8% in upper, 80.7% in middle, and 61.0% in lower reaches, respectively. 2. Infection rates of the metacercariae of Exorchis oviformis, Metagonimus yokogawai, Echinochasmus japenicus, Metorchis orientalis and Clonorchis sinensis in the fishes were 48%,29%, 115, 7.9% and 6.3oA, respectively. 3. The average number of the encysted larvae of Clonorchis found in fish body/gram showed 4.44 in Pseudorasbera larva, Gnathepegon coreanus (1.2), Microphysogoio yaluensis (0.76), Abbottina springeri (0.4), Acanthorhodeus asmussi (0.21) and Cultriculus eigenmanni (0.17), respectively. 4. The average number of the metacercariae of Metagonimus found in fish body/gram disclosed 34.01 in Zacco platypus, Zacco temmincki (16.46), Carassius carassius (5.35), Moroco oxycephalus (1.54) , Aphyocypris chinensis (1.5) and etc., respectively. 5. Detection rates of the eggs of Clonorchis and Metagonimus among residents were 1.1% and 0.8%, respectively, out of a total 923 Persons.