The possibility of albino rats as the hosts of 3 species of the lung-flukes is experimentally detected. Rats were each orally infected with 10 to 20 metacercariae of the bisexual type of P. westermani, P. miyazakii and P. mexicanus and were necropsied 60 to 150 days after infection. All of the worms of P. westermani and a part of P. miyazakii (21 %) and P. mexicanus (74%) were found in the muscles of the rats. They were morphologically similar to excysted metacercariae and contained many excretory granules in their bladder. Worms of the youngest stage selected from them were fed to dogs and cat and 37.3-66.7% of worms were recovered from the animals after 103-202 days. These worms were parasitic within cysts in the lungs and most of them were fully mature. Thus, it was revealed that the bisexual type of P. westermani, P. miyazakii and P. mexicanus also take the rat as their paratenic hosts.