Background/Objective: Flexible ureterorenoscopy with laser lithotripsy is an attractive treatment option for renal stone: residual postsurgery, ESWL resistant, movement back into kidney in ureteroscopy, hard position for open surgery... The study aims at evaluating initial results of flexible ureteroscopy in treatment of renal stone and to learn the experience. Materials and methods: 22 patients with kidney stones treated with flexible ureteroscopy, using Holmium Laser energy to break stones. Results: The free stone rate was 63.63 percent (14/22 cases). 20/22 patients were inserted ureteral catheter in at least 1 week before the procedure. No serious complications. Conclusion: Flexible ureteroscopy is good and effective method for treatment of renal stone, especially for the cases treated with surgical procedures before. Ureteral catheter is a factor to help inserting the flexible ureteroscope easier.