Effects of Sardine Oil Feeding and Vitamin E Supplementation on Histopathological Changes and $alpha$-L-fucosidase activity in experimental hepatocarcinogenesis. Sprague-Dawley rats weighing 80~90 g were fed the diet containing either 15% corn oil (CO) or sardine oil (SO) with or without vitamin E supplements (dl-$alpha$-tocopherol acetate 800 IU/kg diet) for 8 weeks. After 2 weeks of feeding, the rats were given a single intraperitoneal injectin of diethylnitrosamine (DEN, 200 mg/kg BW). From the fifth week, rats were given 0.02% acetylaminofluorene (AAF) in diet for 4 weeks. At the seventh week, 0.05% phenobarbital in liver and hepatic glutathione S-transferase palcental form positive (GST-P+) foci were examined by Hematoxylin& Eosin (H&E) staining and immunohistochemical method, respectively. Serum $alpha$-L-fucosidase activity was determined. The livers fromt he carcinogen treated rats showed significantly increased formation of GST-P+ foci at sacrifice points while the livers fromthe non-carcinogen treated groups showed almost no foci. Although GST-P+ foci formation was not affected by dietary oil, it was increased unexpectedly by vitamin E supplementation. Histopathological changes were similar to patterns of GST-P+ foci formation in almost all groups. Serum $alpha$-L-fucosidase activities were increased by carcinogen treatment in all dietary groups. $alpha$-L-fucosidase activities were positively correlated with GST-P+ foci formation. There results suggest that excessive vitamin E supplementation can enhance hepatocarcinogenesis although the mechanisms involved are not clearly understood.