Abstract: Objective To investigate the effect of IL-6 inducing murine bone marrow neutrophils MMP-9 production and releasing and its mechanism of activation. Methods Murine bone marrow neutrophils were separated and cultured in vitro and randomly divided into four groups: control group, IL-6 50ng/ml stimulation group, IL-6 50ng/ml+DMSO group and IL-6 50ng/ml+STAT3 inhibitor Ⅷ 50μmol/L group. RT-PCR method was used to evaluate the mRNA level of intracellular MMP-9 of neutrophils. Gelatin zymography was performed to detect the activity of MMP-9 released from neutrophils. Western blot was applied to test the phosphorylation levels of STAT3 pathway in neutrophils. Results Compared with control group, the administration of IL-6 enhanced the mRNA expression of MMP-9(P=0.0050); the activity of MMP-9 released from neutrophils was elevated(P=0.0087) and the p-STAT3 levels in neutrophils was also increased (P=0.089). After the STAT3 inhibitor Ⅷ was added, the mRNA expression of MMP-9, the activities of MMP-9 in the supernatant and the p-STAT3 levels in neutrophils were decreased significantly than those in the IL-6 group (P=0.0067, 0.048 and 0.098, respectively). Conclusion IL-6 induces the production and releasing of MMP-9 in neutrophils and the effect may be induced by the activation of STAT3 pathway.