Percutaneous nephrostomy was performed in 82 patients under the fluoroscopic guidance for recent 3 years. The caused of hydronephrosis were as follows : unknown origin of stricture (N-37), stone (N=20), tumor (N=14), tuberculosis (N=8), postoperative ureteral injury (N=1), postoperative anastomotic stricture (N=1) and renal transplantation complication (N=1). successful nephrostomy was achieved in 79 patients (96%). Causes of failure were minimal dilatation of pelvocaliceal system (N=2) and staghorn calculi (N=1). Follow up laboratory test shows high BUN and creatinine level returned to normal limit within 1 or 3 weeks in 73 patient. Major complication was not found, but temporary hematuria (N=4) or fever (N=1) was noted. In conclusion, percutaneous nephrostomy is the safe and effective method for the temporary and permanent relief of urinary obstruction and the maintenance of ureteral patency.