ObjectiveTo investigate the necessity of indwelling ureteral stent before flexible ureteroscopic lithotripsy in the treatment of upper urinary tract calculi. MethodsEighty-five patients with upper urinary tract calculi treated between June 2013 and December 2014 were divided into two groups:group A (without indwelling stent, n=42) and group B (with indwelling stent, n=43).Incidence of stent-related urinary tract symptoms, operation time, one-time success rate of placement for ureteral access sheath, and stone clearance rate were compared between the two groups. ResultsThe operation time and stone clearance rate had no statistically significant differences between the two groups (P > 0.05).The incidence of stent-related urinary tract symptoms and one-time success rate of placement for ureteral access sheath in group B were significantly better than those in group A (P < 0.05). ConclusionFor one-phase operation success, we suggest that indwelling ureteral stent is necessary before flexible ureteroscopyic lithotripsy for treating upper urinary tract calculi.