Are-examination of feces for helminth eggs among school-children in 1967, 7 years after the initial examination, showed a remarkable decrease of the prevalence of clonorchiasis in Yamamotogun, Akita Prefecture. Such decrease would be mainly due to the reduction of Clonorchis metacercariae in fresh water fishes obtained from the Asanai-numa pond and partly to the decrease in the consumption of them by inhabitant living around the pond.
