Exposure to complement-activating cellulosic dialysis membranes has been claimed to adversely affect the course of acute renal failure. To test this hypothesis, male Sprague-Dawley rats were allocated to two groups: in group I, acute renal failure was induced by bilateral renal artery clamping, while group II animals underwent a sham procedure. In each group, the rats were further allocated to undergo hemodialysis with either a Cuprophan, a Hemophan, or a PAN miniDialyzer membrane 3 and 7 days after surgery or no dialysis. The renal function was measured by inulin clearance on the days following dialysis. Temporary occlusion of the renal arteries led to a rapid increase in serum urea and creatinine levels that peaked between 24 and 48 h after surgery and declined slowly thereafter. Peak urea values were similar in the acute renal failure groups. The hemodialysis sessions were well tolerated. Degree and rate of recovery were similar in all acute renal failure groups irrespective of whether they underwent dialysis or not or the type of the dialysis membrane. Complete recovery was observed in all the acute renal failure groups by the end of the observation period. Our findings refute the hypothesis that in ischemic acute renal failure exposure to complement-activating cellulosic dialysis membranes impairs the recovery of renal function.