Flexible ureterorenoscopy is recommended for the treatment of inferior calyx stones, 10 to 15 mm in diameter, particularly after failure of extracorporeal lithotripsy. It is recommended to mobilize an inferior calyx stone towards the renal pelvis or superior calyx before starting fragmentation. This manoeuvre is essential to preserve the ureterorenoscope. The objective of this technical note is to explain the stone "relocalization" manoeuvre and describe how in situ treatment of an inferior calyx stone can be dangerous for the flexible ureterorenoscope.