Platelet activating factor is involved in warm ischemic damage. We studied the effect of the PAF receptor antagonist BN 52021 in an experimental model of 60 min of renal warm ischemia in which the left kidney was flushed with Euro-Collins solution and a right nephrectomy was performed. Eighty Wistar rats were divided into a sham-operated group, two control groups, and four study groups, according to the dosage and route of BN 52021 administration. BN 52021 was used in the flush solution at concentrations of 0.1 and 0.5 mg/ml, or intravenously prior to ischemia at 5 and 10 mg/kg body weight. Creatinine clearance per 100 g body weight, fractional sodium excretion, and conventional histology were studied. Rats that received BN 52021 intravenously showed a significantly higher creatinine clearance than controls. Intravenous BN 52021 produced a higher acceleration of renal function recovery at 10 mg/kg than at 5 mg/kg body weight. Conventional histology was better in animals that received BN 52021 at 10 mg/kg body weight than in controls. Addition of BN 52021 to Euro-Collins flushing solution showed no protective effect. We conclude that intravenous BN 52021 shows a renal protective effect against warm ischemia.