The present study was undertaken to observe the pathologic changes of the liver in albino rats with Clonorchis sinensis.

Twenty five rats given 50 metacercariae respectively by mouth were autopsied at 3 days (group 1), one week (group 2), 4 weeks (group 3), 8 weeks (group 4) and 12 weeks (group 5) of infection.

The following results were obtained:

1.Parasites were seen in bile ducts of group 2, 3, 4, 5 and increased in number with duration of infection.

2. The pathologic changes in the liver were prominent in intrahepatic bile ducts. Epithelial cells of bile ducts showed definite atypia and proliferation resulting in pseudostratification in group.

3. Stratification of metaplastic squamous cells and glandular proliferation were prominent in group 3. The epithelial cells were keratinized with syncitium and cribriform formation in group 4 and almost suggestive of adenomatous hyperplasia in group 5. Periductal fibrosis seen in group 4 was considerable as well as mature with hyalinized connective tissue in group 5.

4. Heavy inflammatory cell infiltrations around the affected bile ducts in group 1 became smaller in number with duration of infection. The inflammatory cells consisted of the majority of eosinophils in group 1 and chiefly plasma cells, lymphocytes and mononuclear cells in group 5.

5. Veins in portal spaces dilated markedly in group 1 became less prominent with duration of infection.

6. Although portal fibrosis increased definitely in group 3 often extended into the hepatic lobules in group 4, the changes of hepatic cells, sinusoids and central veins were negligible.

Above results suggest that clonorchiasis could be a factor in inducing primary carcinoma of liver in albino rats.