Objective      To evaluate the safety and curative efficacy of flexible ureteroscopy (FURS) with holmium laser lithotripsy in the treatment of renal stones of 2 cm or greater in length-diameter.       Methods      A total of 68 patients who had the renal calculi of 2 cm or greater in length-diameter were treated with FURS in our department from March 2014 to August 2015 were enrolled in this study. The stone-free rates after 1 procedure

and complications were collected and retrospectively analyzed.       Results      The one-time successful rate of ureteroscopic insertion was 100%

and the successful rate of stone finding was 100%. After 1 procedure

the percentage of stone-free patients was 86.76%

and the stone-free rate was 90.9% for those with stones of 2～3 cm in size

and 69.20% for those with stones ＞3 cm. The total complication rate was 7.35%

and was 7.27% and 7.69% respectively for those with stones of 2～3 cm

and ＞3 cm. One case had renal hemorrhage during operation and was improved after conservative treatment. Two cases occurred post-operative ureteral stone street

and the stones were removed successful after emergency operation. Post-operative fever occurred in 4 cases. Two of them were due to ureteral stone street and were improved after emergency operation

and the other 2 cases with fever were improved after anti-infective therapy. No severe complication happened

such as severe hemorrhage and septic shock in all the cases.       Conclusion      FURS with holmium laser lithotripsy is another favorable option for eligible patient and experienced urologists in treatment of renal stones of over 2 cm in size.