Objective:To investigate the influence of interleukin-18 (IL-18) on the rat deep vein thrombosis (DVT). Methods:Viral vectors of IL18-pCDH-GFP/IL18-LMP-shRNAmir1 were constructed. SD rats (n=27) were randomly divided into IL-18 overexpression group,IL-18 inhibition group and control group which were injected with 100 μl IL-18 overexpression lentivectors (IL18- pCDH-GFP),100 μl IL-18 inhibition retroviral vectors (IL18-LMP-shRNAmir1),100 μl saline,respectively,into the tail vein. All rats’ inferior vena cavas (IVC) were modeled as “stenosis” to promote IVC thrombosis after 24 h of injection. The weight and length of IVC thrombosis after 24 h of modeled were investigated,and the expression of IL-18 in the venous wall was measured by real-time PCR assay. Results:IL18-pCDH-GFP and IL18-LMP-shRNAmir1 vectors showed the ideal overexpression/inhibition rate in vitro. All groups had stabilized thrombus formation after modeled 24 h. The average length and weight of thrombus in the IL-18 overexpression group were significantly higher than those of other groups (P < 0.05). The level of IL-18 in the overexpression group was remarkably higher than that of other groups in the vessel wall (F=3.784,P < 0.05),which was proved by real-time PCR assay. Conclusion:IL-18 promotes thrombus formation in rats,and inhibition of IL-18 reduces the thrombus formation. IL-18 may be related to the development process of DVT and its proinflammatory effect may play a vital role in the pathogenesis of VTE.