【Abstract】 Objective To evaluate continuous blood purification in the treatment of pregnancy with acute renal failure. Methods Eighteen pregnant women with acute renal failure were treated with continuous venovenus hemodiafiltration. APACHE II score and plasma BUN, Cr, K+, Na+, Cl-, Ca2+, CRP and pH were measured before and after the treatment. IL-6 and TNF-α concentrations in serum and in outflow fluid were measured by radioimmunoassay before the treatment and after the treatment for 12 and 24h. Results Among the 18 patients, 16 cases recovered, one case died, and one case progressed to become chronic renal failure. After the treatment, plasma BUN and Cr decreased (P<0.05), WBC, plasma electrolytes and pH returned to be normal, and APACHE II score, and plasma CRP, IL-6 and TNF-α were lower than those before the treatment (P<0.05). Conclusion Early continuous venovenus hemodiafiltration can improve the clinical conditions of pregnant women with acute renal failure. The therapeutic benefit may relate to the clearance of over-expressed IL-6 and TNF-α, resulting in the decrease of inflammatory activity and the balance between inflammatory and anti-inflammatory factors.