Abstract: DDB is a hepatoprotectant and has been widely used for the treatment of chronicviral hepatitis in China,The drug markedly improved the abnormal liver ft1nction particularly inlowering the elevated serum transaminases in patients.It is k nown that there is a close correlationbetween primary hepatocarcinoma and chronic viral hepatitis.The aim of the present study is toevaluate the effect of DDB on hepatocarcinoma cell line.The results showed that the growth andclonogenicity of Bel-7402 human hepatocarcinoma cell line cuItured with DDB were markedlyinhibited.The nucleoles of the cells treated with DDB disappeared or their numbers and nucleus/cytoplasm ratio decreased under electron microscopic observation, DDB at the concentration of 10-mol·L^-1 significantly increased the contents of cAMP and calmodulin(CaM)in Bel-7402 hepatocarci-noma cells.DDB was also found to inhibit topoisomerase II activity of Bel-74 02 hepatocarcinomacells.These results suggest that the mechanism of inhibition of DDB on several phenotypes of Bel-74 02 cell line may be related to its effect on cAMP and CaM content as well as topoisomerase IIactivity.