The advantages of percutaneous nephrostomy include (1) achieving rapid, safe drainage of an obstructed collecting system with use of local anesthesia and sedation rather than general anesthesia, and (2) facilitating use of antegrade pyelography under fluoroscopic guidance to determine the cause of the obstruction. In addition, during temporary diversion the functional status of the obstructed kidney can be evaluated. If function is adequate, a pyeloplasty or reimplantation of a ureter may supplant nephrectomy. Use of percutaneous nephrostomy is a relatively new technique for treatment of obstructive uropathy in children. In the case reported here of an 8-year-old girl with a duplicated right collecting system and distal obstruction of the upper pole ureter, the procedure offered a rapid and safe alternative to surgical insertion of a nephrostomy tube.