Abstract： Objective To prospectively evaluate the effect of hemodiafihration with different amount of sub-stitute fluid on expression and function of Toll-like receptor on peripheral blood monocyte in severe septic patients. Method Thirty severe septic patients accepted in ICU of Shaoxing People's Hospital from March 2006 to Febru-ary 2009 were qualified for bundle strategies therapy plus hemodiafiltration, and they were randomly derided into two groups with fifteen persons in each one: high volume hemofiltration group (HVHF4 L/hr) and continuous points of hemofihration treatment(0 h,6 h, 12 h,24 h,48 h) ; Toll-like receptor-2(ILR2), receptor-4(TLR4) mR-monocytes were isolated 24 h after hemofihration and underwent incubation in vitro with stimulation of (lipopolysac-charide)LPS;the expression of TLR2/TLR4 mRNA and protein were determined at 6 h,12 h,24 h and 48 h point of incubation repectively;and the levels of TNF-α, IL-6, IL-8 in the substrate fluid were also tested by ELISA. All the data were presented as x±s and analyzed by t-test or one way ANOVA. Results The expression of TLR2/ TLR4 mRNA and protein more deereased in HVHF group (P < 0.05). The levels of TNF-α, IL-6, IL-8 secreted by the incubated monocytes in each specific time point varied in terms of the amount of substitute fluid: CVVH > HVHF > controlled group (P < 0.05). Both the expression of TLR2/TLR4 mRNA and protein on surface up-reg-ulated at each time point: controlled group > HVHF> CVVH (mRNA P <0.05; protein P >0.05). Conclu-sions HVHF could improve the function of monocytes to partially recover the celluar-immunity and may play a role in restoration of imrnunal homeostasis in septic patients.