Metacercariae of Metagonimus hakubaensis Shimazu, 1999 （Digenea: Heterophyidae）were obtained from the lamprey Lethenteron reissneri （Dybowski）（Agnatha: Petromyzontidae） collected in the stream at Kamishiro, Hakuba village, Nagano prefecture, central Japan. They were experimentally fed to golden hamsters. Gravid adult worms were recovered from the small intestine of the golden hamsters 22 days after infection. The adults were fixed in hot formalin, stained and mounted in Canada balsam. Whole-mounted adults were described and compared in morphology with the slightly flattened type series. In the present specimens, the ventral sucker was usually slightly larger than or as large as, or rarely slightly smaller than, the oral sucker; and the sucker ratio was 1: 0.94―1.21 instead of 1: 0.75―1.06 in the slightly flattened type series
