We reviewed the clinical histories of 14 patients diagnosed of acute obstructive renal failure due to bilateral or unilateral uric calculi in patients with only one functioning kidney for a period of 14 years (1974-1987). Urine was alkalinized in all patients. The increase in urine pH was effective in resolving the obstruction in 12 patients. The alkalinizing methods which succeeded in permeabilizing the urinary tract, considering each functioning kidney independently were: intravenous in 5/21, upstream urethral catheterism in 9/21 and by nephrostomy catheter in 5/21. Surgery was performed in 2 patients. In the later the calculi were of double composition. The most frequent complications were: urinary infection in 7/14 patients, chronic renal failure in 4/14 patients, sepsis in 3/14 patients and bacteremia in 2/14 patients. None of the patients died.