We have described a male patient with a episode of acute renal failure after strenuous exercise. He was found to have low serum uric acid(0.6 mg/dL, after recovery) and normal 24 hour urinary excretion in the steady state. The possibility of other diseases that cause hypouricemia could be excluded, acute renal failure associated with idiopathic renal hypouricemia was diagnosed in this case. A renal computed tomography showed the delayed wedge shaped contrast enhancement, these findings suggested that the cause of acute renal failure could be renal vasoconstriction rather than obstruction by uric acid crystals. Hypouricemia appear to play a crucial role in this reperfusion oxygen free radical induced acute renal failure. We have suggested that the renal hypouricemia should be suspected in the case of acute renal failure associated with exercise when the patient`s uric acid level was within or slight alone normal range at the time of acute renal failure. (Korean J Nephrol 2002;21(2):312-316)