Abstract: Objective: To explore the influence of veno-venous hemodiafiltration(VVHDF) on plasma cytokines in patiens with multiple organ dysfunction syndrome(MODS).Methods: A double lemen catheter was put into the femoral vein of 55 patiens with MODS,and the VVHDF was performed with the Hospal BSM 22 SC.The level of serum BUN,Cr,K⁺ and arterial blood gas was measured before and after VVHDF,and the plasma TNF-α,IL-1,IL-6,IL-8,IL-10 was measured by ELISA at 0,1,3,6,24 hours after VVHDF. Results: The level of serum BUN,Cr,K⁺ decresed significantly,HCO₃^-in creased,after VVHDF(P<0.001),The plasma concentration of IL-1,IL-8 and IL-10 decreased significantly(P<0.01),The plasma concentration of IL-6 was lower at 1 hours after VVHDF than before VVHDF and 24 hours after VVHDF.There was no significant difference in the plasma concentration of TNF-α at any time before and after VVHDF(P>0.05).Conclusions: VVHDF can improve the blood biochemical markers of the patients with MODS and remove some cytokines in plasma.