Objective To investigate the effect of syntenin-1 on the assembly of hepatitis C virus (HCV) particles. Methods The content of syntenin-1 in human primary hepatocytes was detected by Western blotting analysis. Human hepatocellular carcinoma cell line Huh7.5.1 was transfected with lentiviral plasmids to construct syntenin-1 overexpressed cell line and green fluorescent protein (GFP) overexpressed cell line. After transferring HCV RNA into Huh7.5.1 cells, syntenin-1 overexpressed cells and GFP overexpressed cells by electroporation, the effects of syntenin-1 overexpression on HCV in the cells were investigated in terms of RNA replication, viral protein contents and secretion of infectious virus particles by luciferase analysis, Western blotting and virus titer, respectively. The density of viral particles was assessed by isopycnic ultracentrifugation to analyze the distributions of HCV RNA and infective titer. Results The contents of syntenin-1 in three human primary hepatocytes were higher than that in the Huh7.5.1 cells (P<0.01). Syntenin-1 overexpression had no effect on HCV RNA replication in host cells; the infectivity of HCV derived from syntenin-1 overexpressed cells was not significantly different compared with the Huh7.5.1 cells or GFP overexpressed cells. In syntenin-1 overexpressed cell culture supernatants, some infectious HCV particles mainly concentrated in the region of concentration of 1.08-1.16 g/mL gradually transferred to the low-density region of 1.01-1.02 g/mL. Conclusion Syntenin-1 overexpression alters the distribution of density components of infectious HCV particles.