Hepatic tumorigenesis was induced by ad libitum feeding of diethylnitrosamine (DEN) only. We could also observe hepatic tumor induction in 100% of DEN treated rats without any other cocarcinogen. The liver specific enzyme activities (AST, ALT, ALP, ${gamma}$-GTP) were significantly increased (P<0.05) in all treated groups compared to control and induced apoptosis groups. In histopathological analysis, the altered foci, hyperplastic nodules, neoplastic nodules, adenomas and carcinomas were observed in liver tumors induced by administration of DEN in rats. Lipopolysaccharide-induced apoptosis in D-galactosamine sensitized mice was investigated in hepatocytes in vivo. Typical morphological changes of apoptosis were detectable in liver 12 hr and 24 hr after the injection of Lipopolysaccharide (5 $mu extrm{g}$) and D-galactosamine (20 mg) to mice. It was suggested that organ specific enzyme activities and morphological findings might be very useful for understanding the role of hepatic tumorigenesis including the apoptotic cell death.