"High burden stones" include single or multiple large calculi (altogether surface area > 300 mm 2, or largest diameter > 20 mm), and staghorn calculi (any branched stone occupying more than one portion of the renal collecting system, i.e. pelvis with one or more calyceal extensions). Since clinically threatening, their active removal is mandatory. All updated guidelines recommend four modalities as potential treatment for large/staghorn urolithiasis, including PNL monotherapy, ESWL monotherapy, combinations of PNL and ESWL, and open surgery. The technical enhancement and increasing spread of PNL, ESWL and ureteroscopy in the past twenty years has led to displacement of the surgical therapy of renoureteral calculi in the daily urological practice (nowadays 1-5.4% of cases in developed countries and in well-equipped, dedicated centres), but open or laparoscopic management of urolithiasis is still a viable option that should be considered in few, highly selected circumstances. Currently, PNL is the preferred first-line, minimally invasive treatment for complete one-step removal of high burden urolithiasis. It has been suggested that two or more access sites may be required for complete clearance, yet implying greater blood loss. The use of single-tract PNL with adjuvant procedures such as flexible ureteroscopy/nephroscopy may decrease the disadvantages of the multiple-tract PNL without compromising on stone-free rates. ECIRS (= endoscopic combined intrarenal surgery) is a new, versatile approach for the treatment of large and/or complex urolithiasis. Combining the anterograde and retrograde approach to the renal cavities, ECIRS allows the combined use of all the rigid and flexible endourological armamentarium, and optimal endovision percutaneous renal puncture, preliminary evaluation of renal stones features, negligible need of multiple percutaneous accesses, immediate treatment of concomitant ureteral calculi or ureteropyelic junction stenoses; final visual control of the stone-free status. ECIRS is usually performed in the Galdakao-modified supine Valdivia position, the only patient position supporting this comprehensive attitude of the urologist towards upper urinary tract pathologies. Optimal planning of a safe and effective ECIRS procedure also benefits from an accurate preliminary three-dimensional study by means of tomography urography of the pelvicalyceal anatomy (which is complex and often highly variable) and of the stone features (site, number, size).