Abstract: Objective To study the bcl-2 and bax expression of liver cells during liver precancerous lesion.Methods The rat liver precancerous lesion models were established by injecting diethylnitrosamine(DEN) intraperitoneally.Liver pathological characteristics was examined with microscope.Alamine aminotransferase(ALT),aspartate amiotransferase(AST),γ-glutamyl transpectadase(γ-GT),α-L-fucosidase(AFU),alpha-fetoprotein(AFP),and carcinoembryonic antigen(CEA) contents in serum were measured with biochemical technology.The expression and quantitative analysis of bcl-2 and bax were conducted with immunohistoehemistry and reverse transcription(RT)-PCR.Results Compared with the control group,ALT,AST,γ-GT,and AFU content in serum of DEN group were increased(P < 0.01 for all),while AFP and CEA content in serum remained unchanged.In fourth and twelfth week of DEN treatment,the expression of bcl-2 in rat liver cells were 121.45±6.53 and 120.24±9.63,lower than that of the control group(P > 0.05 for all),and the expressions of bax were 49.58±5.23 and 64.28±2.86,higher than that of the control group(P < 0.05 for all).The bcl-2/bax ratios were 2.45 and 1.87,lower than 3.83 of the control group(P < 0.05).Conclusion The expressions of bcl-2 and bax might be involved in the development of liver precancerous lesion.The expressions of bcl-2 and bax may serve as auxiliary diagnosis markers for liver precancerous lesion.