ObjectiveTo investigate the effects of somatostatin8 (SS8) on the apoptosis and the expression of cmyc protein of hepatocellular carcinoma cell SMMC7721. MethodsCultured in vitro, hepatocellular carcinoma cells SMMC7721 were incubated with SS8 (10 μg/ml). The apoptosis rate and expression of cmyc protein were detected by flow cytometry (FCM). ResultsSS8 can cause the spanonumber in S and G2/M phase and the auxonumber in G0/G1 phase of SMMC7721 cells . The apoptosis rate was 14.2% in the study group and 6.1% in the control group, and there was significant difference (P<0.05); The level of expressions of cmyc protein was 0.833±0.035 after action by SS8 for 24 h. Compared with control group, there was no significant difference in the study group(P>0.10).But after the cells were incubated with SS8 for 48,72,96,120,144 h, the level of expressions of cmyc protein was 0.818±0.04,0.721±0.029,0.669±0.026,0.648±0.045,0.642±0.028 respectively in the study group, and there was significant difference as compared with the control group (P<0.05). Conclusion The SS8 can induce the apoptosis and lower expression of cmyc protein of hepatocellular carcinoma cell SMMC7721.