Binh Dan hospital has performed and approved to use the flexible ureterorenoscope for the treatment the upper urinary tract stones. Materials and methods: In the period time from February to July 2009, a series of 10 patients with proximal ureteral calculi combined small kidney stones, underwent holmium: YAG laser trypsy with a 7.5 Fr flexible ureteroscope under the guidance of a 3 Fr ureteral catheter.