OBJECTIVE To evaluate the efficacy and safety of mini- percutaneous nephrolithotomy (PCNL) in the treatment of large impacted proximal ureteral stones. METHODS We retrospectively reviewed the outcomes of 163 patients who underwent mini-PCNL between January 2006 and August 2010. Mean age was 48.6 years and mean stone size was 18.4 mm. Hydronephrosis and/or hydroureterosis appeared in all patients. In the prone position, percutaneous access (16-Fr sheath) was established by placement of an access needle into the intended calyx under fluoroscopic guidance or combined with ultrasound guidance for complete obstruction by stones while the contrast agent cannot transit. Pneumatic or ultrasonic probes were used throughout ureterorenoscopy for lithotripsy. The ureteral stents and nephrostomy tube were placed at the end of the procedure. Mean drop in hemoglobin, operative time, success rate, hospital stay, and complications were assessed. RESULTS Mini-PCNL operations were performed successfully in all patients. Mean operation time was 37 min. Mean postoperative hospital stay was 3.6 days. All cases were followed up for 6-20 months. No major complications like hemorrhage, perforation or organic injury were noted during the operation or postoperatively. The stone-free rate in all patients was 95.7%. Calculus had no recurrence during the follow-up period. Hydronephrosis and hydroureterosis disappeared or were relieved. CONCLUSIONS Mini-PCNL is a safe and effective therapy for large impacted proximal ureteral stones.