Helminthological examination was made on 42 individuals of Polypedates leucomystax captured on Miyakojima of the Miyako Group, Ryukyu Archipelago, Japan. Eight species (one digenean, five nematodes, one acanthocephalan, and one oligochaete) were recognized, of which one nematode Strongyloides sp. characterized by the presence of an isthmus in the esophagus, seemed to have been newly adopted by P. leucomystax from herpetofaunal elements native to Miyakojima. Meanwhile, Raillietnema rhacophori and Allodero sp. were considered to have reached this island by accompanying P. leucomystax from the Central Ryukyus. Present specimens of R. rhacophori differed from conspecific specimens from the Okinawa Group and Malaysia in a few morphological characters, presumably as a result of bottlenecks through the host's dispersals involving a limited number of worms.