Pelvi-ureteric junction obstruction has been treated in 3 patients using a percutaneous modification of the Davis intubated ureterostomy technique. A 10-French tube is introduced into the obstructed upper ureter through a percutaneous nephrostomy puncture. Full thickness incision of the upper ureter and pelvi-ureteric junction is then carried out using a standard endoscopic urethrotome. The splint tube and diverting proximal nephrostomy remain in situ for 1 month. Good drainage was established in 2 cases following de-tubing. Further cases are under study.