OBJECTIVE To determine an efficient method for treating upper ureteral impacted stones, we compared the outcome of minimally invasive percutaneous nephrolithotomy with the aid of our patented system and transurethral ureteroscopy. MATERIALS AND METHODS A total of 182 patients with complicated impacted upper ureteral stones above the level of L4 were randomly divided into 2 groups. Group 1 included 91 patients who were treated with minimally invasive percutaneous nephrolithotomy with the aid of a patented system. Group 2 included 91 patients who were treated with ureteroscopy. The patients underwent postoperative shock wave lithotripsy, when necessary. The operative time, stone clearance rate, operative complication markers (amount of intraoperative bleeding and postoperative fever rate), and cost of treatment were compared. RESULTS A significantly shorter operative time, greater rate of stone clearance, lower need for postoperative shock wave lithotripsy, and lower rate of postoperative fever was found in group 1 than in group 2 (P < .05). However, the cost of treatment and amount of intraoperative bleeding were significantly greater. CONCLUSION We believe minimally invasive percutaneous nephrolithotomy with the aid of the patented system could be the first choice in treating complicated impacted upper ureteral stones above the level of L4. UROLOGY 80: 1192-1197, 2012. (C) 2012 Elsevier Inc.