Genus Metasonimus has been a subject of taxonomic debates for several years. In morphological aspects, M. vokogawci has been thought to have three subtypes, namely Yokogawa type (M. yokogawai in strict sense) , Miyata type and Koga type. But dif- ferences in the intestinal pathology induced by these subtypes have not been studied yet. In this study we compared the pathological reactions inducted by M. yokoBnwai and Metcgonimus Miyata type using proliferating cell nuclear antigen (PCNA) index. Metacercariae (Mc) of M. yokogcuani were collected by artificial digestion of Plecoslossw oLtiveLis and Mc of Metngonimus Miyata type were collected from Zacco pEntvpus. Three hundreds Mc of each species were infected orally to ICR mice. The mice were sacrificed at 3, 6. 10. 16 and 23 days after infection and the small intestines were resected into three portions (proximal. middle, and distal) . Immunohistochemical staining for PCNA was done using PC-10 (DAKO-PCNA, CA, USA) The PCNA indices in M. Wokosnwci infected group on the 6th and 23rd day after infection were lower than in the control and Miyata type infect ed groups (p < 0.05) from all of the three intestinal regions. On the other hand, the control group and Ifetngonimus Miyata type infected group did not make any differences in PCNA indices. The villus/crypt WIC) ratio was also decreased significantly in M. Wokogcwni infected mice but not in Metagonimus Miyata type infected ones. It is suggested that M. wokogawci induce villous atrophy through a decrease in the cell proliferation at the crypt. The results of this study suggested that M. WokoBnwai induce more serious intestinal pathology than Metcsonimuf Miyata type. Key words: Metagonimus yokogawai, Metagonimus Miyata type, pathology, PCNA