The purpose of this study was to evaluate the protective effect of Kamicheonggan-tang(KCGT) on pre-hepatocarcinogenesis induced by N-nitrosomorpholine. The studied using blood chemistry, lipidperoxidation, antioxidant, immunohistochemistry and morphological change. The results were obtained as follows. In the pre-hepatocarcinogenesis induced by NMP, serum AST, ALT, ALP and total bilirubin were not changed in NMP and NK treated group after 1 st week, but desreased in NK treated group after 4th week as compared with NMP treated 4th week group. The content of GSH was similary to in NK treated groups as compares with data of normal group. The content of MDA was increased in NK treated group after 1st and 4th week, and more increased in the NMP treated group than those of their NK treated group. The immunohistochemically, stain of GST-p, positive lesions of KCGT were significantly decreased than those of NMP treated group. The histopathologically, fat changes, nucleotic changes, oval cell and inflammatory cells in periportal were observed in NMP treated fater 4th week, but those were significantly decreased from 4th week in the NK treated group. And the enlarged nucleus was not changed in KCGT treated group, but increased in NMP treated group after 1st and 4th week. The ultrastructurally, nucleotic changes, glycogen degeneration, lipid droplet and rER fragmentation were observed in NMP treated group after 4th week, but those changes were significantly decreased from 4th week in the NK treated group. These results suggested that KCGT extracts has protective effect on prehepatocarcinogenesis by NMP, might be usefully applied for clinical treatment of hapatic disease and also it was necessary to do more studies about its mechanisms.