The effects of hemofiltration on cerebral resuscitation were studied by using resuscitation model of potassemia-induced cardiac arrest and cardiopulmonary bypass. Sixteen rabbits were divided into control group (CG) and hemofiltration group (HFG). Blood lactic acid, lipid peroxidant (LPO), serum iron, middle molecular substance (MMS) were determined. Neurologic deficit score (NDS) system was used to evaluate neurologic function. The level of blood lactic acid was increased in both CG and HFG. It was higher in CG than in HFG (P > 0.05). Serum iron was increased in CG, however, it was decreased in HFG. The difference between the two groups was significant (P < 0.01). LPO was increased significantly in CG and there was no obvious changes in HFG. MMS was increased gradually during reperfusion in CG, whereas it was decreased in HFG. There was significant difference in the corresponding times of the two groups. NDS of CG was higher than that of HFG (32 +/- 12 vs 18 +/- 10) (P < 0.01). These data demonstrate that hemofiltration is able to eliminate ischemic and reperfusional toxic products quickly. Additionally, free iron, agonist factor of catalyzing free radical reaction, does not increase because free radicals and lactic acid are eliminated quickly, inhibiting free radical tissue injury and improving cerebral resuscitation.