Objective To investigate the etilolgy of failed pyeloplasty in children and to study the feasibility of redo laparoscopic surgery for recurrent nreterupelvic junction obstruction.Methods The clinical data of 39 patients with recurrent ureteropelvic junction obstruction after the primary pyeloplasty underwent redo laparoscopic surgery were analyzed retrospectively between September 2009 and June 2016 in our institution.There were 31 males and 8 females with a mean age of 66 months,ranged from 4 to 204 months.28 patients had left obstructions and 11 had fight obstructions,who were diagnosed by ultrasonography,MRU,and MAG3 renal scan et a1.Under general anesthesia,we identified that two patients (5.1％) had renal calices strictures,four patients (10.3％) had unsolved disease ureter and anastomotic strictures,two patients (5.1％) had adhesion band and anastomotic strictures,one patient had adhesion band,high ureteropelvic anastomosis and ureter torsion,and 30 (76.9％) patients had anastomotic strictures.Thirty-three patients underwent cdismembered pyeloplasty,five patients underwent onlay appendiculoureteroplasty and one patient underwent ureterocalicostomy.Results All surgeries were successfully completed without conversion.No intraoperative complication was encountered.One patient had persistent,frequent and intolerable flank pain with severe hydronephrosis after surgery,he subsequently underwent nephrectomy.One patient had persistent severe hydronephrosis which was repaired with on-lay appendiculoureteroplasty.One patient had anastomotic adhesion and balloon dilatation was performed with no further obstruction in follow up imaging.The rest of the patients got complete clinical or radiologic resolution.The successive rate was 36 of 39 (92.3％) at a mean follow up of 25 months (ranging 3-60 months).Conclusions Unsolved ureteric pathologies,anastomotic stricture,renal calices stricture,adhesion band,torsion of ureter and high ureteropelvic anastomosis all contribute to recurrent obstruction after the primary pyeloplasty.Laparoscopic redo pyeloplasty is safe and feasible for skilled surgeons.