Objective      To evaluate the feasibility and safety of flexible ureteroscopic lithotripsy in treatment of intra-renal and proximal ureteral calculi in diameter of 2 cm.       Methods      A total of 79 patients with intra-renal or proximal ureteral calculi in diameter of 2 cm undergoing flexible ureteroscopic lithotripsy with Holmium laser in our department from November 2013 to January 2015 were enrolled in this study. There were 70 cases with stone size ranging from 2 to 3 cm and 5 cases from 3 to 4 cm; 4 cases of staghorn calculi; and 38 cases of multiple stones and 41 cases of single stone. All patients were placed double J stents in 2 weeks before operation

and Holmium laser was used to perform the procedure.       Results      Ureteroscope was inserted successfully in all the patients

so was lithotripsy. The follow-up in 2 weeks post-operatively showed that the stone-free rate was 78.48% (62/79). There were 7 cases receiving lithotripsy twice

1 case for triple times and 2 cases for 4 times

and the mean number of procedures was 1.2 (ranging from 1 to 4 times). The final overall stone-free rate was 88.61% (70/79). After operation

4 cases had  fever

1 had distal ureteral calculi

and 2 had steinstrasse formation. All of them were discharged after corresponding treatment.       Conclusion      Flexible ureteroscopic lithotripsy with Holmium laser is a safe and effective approach for intra-renal and proximal ureteral calculi in size of 2 to 4 cm

and can be used as an alternative option for enal staghorn calculi.