Abstract: BACKGROUND ＆ AIM: In order to observe the anti-carcinoma use of lithium carbonate(Li2CO3) and it's mechanism, the histopathological change and the expression of malondialdehyde (MDA) and 4-hydroxynonenal(4-HNE)protein in Aflatoxin B1 (AFB1)-induced rat hepatic putative preneoplastic lesions alleviated by lithium carbonate(Li2CO3). MATERIAL AND METHODS: One hundred and forty-four healthy Wistar rats (155～175 g) were divided randomly into four groups: normal control group (group A), positive control group (group B), group treated with Li2CO3 simultaneously (group C), group pre-treated with Li2CO3 (group D). The rats were killed in batches in the 6th, 9th or 10th week of the experiment. Histopathological and immunohistochemical assay of MDA and 4-HNE protein was made on hepatic. RESULTS: The condition of rats was significantly improved in Group C and Group D, so do the severity of preneoplasm. Coinciding with the histopathological discoveries, a tendency of "Group B>Group C>Group D>Group A" could be found in observation of MDA and 4-HNE protein expressive, which occurred in the early stage (the 6th week) and significantly increased in the 10 th week. CONCLUSION: It suggested that Li2CO3 has obvious against or restrain lipid peroxidation effect on hepatoma induced by chemicals. The immunohistochemistry assay of MDA and 4-HNE can be used as a sensitive and specialize method to reflect oxidative damage，and it may help early finding and monitoring of hepatoma.

Key words: malondialdehyde, 4-hydroxynonenal, Li2CO3, rat hepatic, preneoplastic lesion