1. Metacercariae of a kind of Levinseniella species were found from a brackish water crabs, Macrophthalmus japonicus de Haan, in the brackish area of Hyungsan river of Kyungpook province. 2. Habitats were the epigastric and progastric regions of Macrophthalmus japonicus. 3. One hundred and seventy five crabs out of 178 examined (98.3 per cent) were infested with metacercariae of Levinseniella species. The infested number of metacercariae in each crabs was average 100 ea. 4. The excystation of metacercaria has not developed in vitro (both saline and tyrode's solution). 5. Many eggs were observed in the metacercariae maintained for 24 or 48 hours in the water-bath. 6. No differences were observed between semi-adult fluke from rat host and those maintained for 24 or 48 hours in vitro.