Aim To investigate the effect of interferon-inducible protein 16 (IFI16) siRNA on the proliferation and apoptosis of interferon-α (IFN-α) induction of human brain vascular adventitial fibroblasts (HBVAF). MethodsThe siRNA of IFI16 gene was transfected into HBVAF in vitro. 48 hours after transfection, the cells were exposed to 2×10⁶ U/L IFN-α for 24 h. Cell cycle and apoptosis were analyzed by flow cytometry. The mRNA and protein levels of IFI16 were measured by real-time PCR and Western blot. Results After transfection with IFI16 siRNA, the expression of IFI16 mRNA and protein levels was decreased in HBVAF, and the cell cycle at G/S transition was promoted.Meanwhile, stimulated with IFN-α up-regulated the expression of IFI16 mRNA and protein levels, and inhibited the cell cycle transition at G/S and promoted cells apoptosis in HBVAF. Such effect was restrained by transfection with IFI l6 siRNA into HBVAF. Conclusion IFN-α may inhibit cells proliferation and promote cells apoptosis of HBVAF by up-regulating the expression of IFI16.