There are a number of eating-houses in the basin of river Ahnseong that sell rawsweetfish, Plecoglossus altivelis, to local residents and visitors. These facts called attention to the possibility of wide spread of metagonimiasis in that area. In an attempt to determine whether the metacercaria of Metagonimus yokogawai does present in the sweetfish caught in the river Ahnseong, a total of 77 fish were examined in the period from April to September 1978. All the fish were infected with the encysted larvae. The average number of larvae persweetfish was 1,815, of which the metacercaria rate for the fluke in the flesh was 56.9 per cent and in the scale, 30.5 per cent. These results indicate that all the sweetfish in the river Ahnseong harbour the metacercaria of Metagonimus yokogawai.
