Retrograde intrarenal surgery (RIRS) has been accepted as the first-line option for surgical treatment of upper urinary tract pathologies including stones and tumors. With the development of surgical instruments with improved deflection mechanisms, visualization, and durability, RIRS has taken on an expanding role in treating urinary calculi located in the upper urinary tract, as it compensates for the shortcomings of shockwave lithotripsy and percutaneous nephrolithotomy. RIRS can also be considered a conservative treatment option for upper urinary tract urothelial cancer or as a means of intensive postoperative surveillance after radical treatment of urinary tract urothelial cancer. RIRS has a steep learning curve and various surgical techniques can be utilized during operations. The use of particular surgical instruments should take into consideration of the gain in surgical efficiency, decrease in complications, and cost-benefit tradeoff.