The organometal cisplatin has potent antitumor properties. However, its use is sometimes complicated by significant nephrotoxicity. This is characterized by tubular necrosis and impairment of the glomerular filtration rate (GFR). On the other hand, it has been demonstrated that atrial natriuretic factor (ANF) increases GFR in normal euvolemic rats. In the present study, we have therefore tested if this new potent natriuretic compound could restore some of the renal parameters affected by cisplatin. To investigate this issue, acute renal failure was induced in 9 rats by intraperitoneal injection of cisplatin 10 mg/kg body weight (b.w.). Renal function was studied 72 h later using the 3H-inulin clearance method and was compared with the renal function of 5 normal euvolemic rats. The cisplatin-treated rats showed high blood urea nitrogen levels, a 74% reduction of whole kidney GFR (0.308 ± 0.047 vs. 1.17 ± 0.08 ml/min/100 g b.w.) and a significant increase in the fractional excretion of urine, sodium and potassium. After 2 control clearances, synthetic ANF was administered intravenously as a prime (12 μg/kg b.w.) and then as a constant infusion (1 μg/kg/min) to 6 cisplatin-treated rats. This promptly doubled the GFR (0.603 ± 0.113 ml/min/100 g b.w.) and induced a significant increase in the excretion rate of urine, sodium and potassium. These results demonstrate that the administration of ANF has a beneficial effect on the experimental model of acute renal failure induced by cispl