Objective To illustrate the possible sy nergistic effect of arsenic trioxide(Ａｓ ２Ｏ ３) and uroacitides on inductio n of apoptosis in hepatocellular carcinoma（HCC）. M ethods HCC cell lines BEL-7402 and Hep G 2 were trea ted with Ａｓ ２Ｏ ３ together with uroacitides for 4 successive days. Cell survi ving fraction was determined by MTT assay, morphological changes were observed b y immunofluorescence staining of Hoechst 33 258, cell cycle and the apoptosis in dex were determined by flow cytometry(FCM). Nude mouse bearing solid liver tumor was used in vivo experiments. Results With uroacitides added at the dosage of 1.0?g/L, apoptotic thres hold of Ａｓ ２Ｏ ３ on hepatoma cell lines was reduced from 5.0??mol/L to 1.0??mol/L (P