Abstract: Eight pigs were experimentally infested with metacercariae, excysted adolescariae and adult worms of P. westermani respectively with dogs as controls. Autopsy was performed at certain intervals varying from 16 to 107 days postinfection. The results were as fol lows: (1) Excysted adolescariae removed from the muscle of infected pigs were only slightly bigger than the metacercariae; (2) P. westermani adult worms separately inoculated into the subcutaneous tissue and the peritoneal cavity of the infected pigs died or atrophied; (3) Some of the adult worms inoculated into the pleural cavities of the pigs were found in the lungs, forming cysts 45 days later. From the above results, the authors suggested that the pig from Wenzhou might be considered as the paratenic host rather than the final host of P. westermani.