Objective：To report a new endourological technique-percutaneous “sandwich” endopyeloplasty for ureteropelvic junction obstruction (UPJO). Methods:In the study, 71 patients with UPJO had endopyeloplasty by percutaneous balloon dilation before and after endopyelotomy, so called “sandwich” endopyeloplasty. The ureter stent was removed after 2 months and all the patients were followed up at least 12 months by ultrasound, intravenous urogram (IVU) or renal scintigraphy. Results: There were 12 patients with primary UPJO, and 59 patients with iatrogenic UPJO after pyelolithotomy, pyeloplasty, ureteroscopic lithotripsy or percutaneous nephrolithotomy. The mean length of stricture was (1.4±0.8) mm while 5 cases had complete stenosis ureteropelvic junction (UPJ). The mean glomerular filtration rate (GFR) of the affected kidney was (19.8±10.8) mL/min.69 patientshad one-stage operation successfully and 2 patients with complete UPJ stenosis were recanalized in the secondary procedures. The mean time of the operation was (39.3±24.2) min. The complications included 1 case of hemotoma, and 2 cases with residual stones. In the follow-up period, 7 patients were re-obstructed. Conclusion:Percutaneous “sandwich” endopyeloplasty shows good results for UPJO of selected patients with simple operation, minimal invasiveness, quick recovery and few severe complications.