We report a case of a 1.5 cm cystine staghorn calculus of the right lower pole in a 32 year female known cystinuric patient. With a 200 microns Holmium laser probe through a 9,5 F flexible ureteroscope the calculus was fragmented in small particles. An internal ureteral stent was inserted at the end of the procedure. All but one small residual fragments were evacuated spontaneously after removal of the stent. This case shows that flexible ureteroscopy combined with the Holmium laser is a safe and efficient procedure to treat medium size renal cystine calculi. It can be repeated in case of recurrence with minimal trauma to the urologic tract.