To investigate the effects of human soluble TRAIL(sTRAIL) on cell growth and apoptosis of hepatocellular carcinoma cell line SMMC7721.After treatment of sTRAIL,the cell proliferation and apoptosis are determined by invertible microscope,trypan blue exclusion test,MTT assay,terminal deoxynucleotidly transferase mediated labeling(TUNEL)and DNA fragmentation assay.Chromatin condensation is observed by invertible microscope,Proliferation of SMMC7721 cell is significantly inhibited after the treatment with sTRAIL,TUNEL results show in comparison with control,the difference of the apoptosis index of cells treated by sTRAIL is significant,and DNA ladder is observed.The results indicate that sTRAIL can induce apoptosis of hepatocellular carcinoma cell line SMMC7721.