Dual siRNA against different regions of gene in hepatitis C virus (HCV) synergistically inhibited replication of HCV RNA. An HCV-infected cell model was established, and HCV RNA and core protein were detected by RT-PCR and Western blot, respectively. Four HCV-specific siRNAs (siCore, siNS3, siNS4B, siNS5B) were designed and transfected into HCV-infected Huh7.5.1 cells. The antiviral efficacies of the siRNAs were compared using real time PCR and agarose gel electrophoresis. HCV replication in infected cells was inhibited by IFN alpha-2b in a dose-dependent manner. Synergistic inhibition effects were achieved with combination treatment of any two of the siRNAs (siCore, siNS3 and siNS5B) at low doses (0.1 and 10 nM), as compared to single siRNA treatment (P < 0.05). Furthermore, CCK-8 assay showed no toxicity of the siRNAs to Huh7.5.1 cells. These findings indicate a promising new therapeutic approach for treatment of HCV.