The objective of this study was to investigate the expression level, clinical significance, and possible regulating role of IL-17F in patients of chronic periodontitis. Periodontal local tissues were obtained from chronic periodontitis (CP) and healthy controls (HC) for real-time PCR (RT-PCR) detection with IL-17F and IL-17A messenger RNA (mRNA). Primary human gingival fibroblasts (HGF) were derived from patients receiving crown-lengthening procedures. Efficiency of small interfering RNA (siRNA) of IL-17R to HGF cells were assessed by Western blot and RT-PCR. Recombinant IL-17F and IL-17A were used to stimulate the HGF cells compared with the control group. Aspects of the nuclear factor-kappa B (NF-κB) and extracellular signal-regulated kinase (ERK) signaling pathways were examined by Western blot. Production of pro-inflammatory cytokines induced by IL-17F and IL-17A was detected by RT-PCR. Statistical analysis was analyzed by SPSS software. It showed significantly elevated levels of IL-17F and IL-17A mRNA in CP gingival tissues compared with HC group (P<0.01). Further analysis showed a significant correlation between IL-17F and IL-17A mRNA in CP group (P<0.05), and both cytokines also correlated with the probing depth (P<0.05). Recombinant IL-17F can induce NF-κB phosphor-p65 and ERK phosphorylation of HGF cells similar to that of IL-17A. Interestingly, we found that both IL-17F and IL-17A could promote the important inflammatory cytokines IL-6, CXCL8, and CCL20 production compared with IL-17R siRNA group (P<0.05). This study indicates that IL-17F may be involved in pathogenesis of periodontitis like IL-17A. The role of IL-17F in disease pathogenesis needs to be further investigated.