Background: Re-do pyeloplasty after failed open or laparoscopic ureteropelvic junction (UPJ) obstruction correction can be a challenging procedure because of scar formation at the previous anastomosis site and decreased vascularity of the ureter. This study compared the perioperative parameters for pediatric robot-assisted laparoscopic (RAL) primary and re-do pyeloplasties with an emphasis on the intra-operative parameters. Materials and Methods: We compared the perioperative parameters of pediatric RAL procedures performed by a single surgeon at a tertiary care children's hospital for both primary ureteropelvic junction obstruction (UPJO) and recurrent UPJO after a previous open or laparoscopic procedure over 2013-2015. The operative time was subdivided as total operative time, console time, port placement time, dissection time to UPJ, and anastomosis time. Results: A total of 65 pediatric RAL pyeloplasty procedures for UPJO were performed (55 primary and 10 re-do pyeloplasties) during the study period. The console times were 43.3% longer for re-do pyeloplasties than for primary pyeloplasties (133.030.7 versus 92.8 +/- 24.0 minutes, respectively, P<.01). The re-do cases had longer operative times, especially for UPJ exposure (52.2 +/- 21.0 versus 28.0 +/- 14.0 minutes, P<.01). There were no conversions to open surgery or significant perioperative complications. There was no difference in hospital pain medication usage and hospital length of stay between the 2 groups. The treatment success rates were 98.2% (54/55) and 100% (10/10), respectively. Conclusions: RAL re-do pyeloplasty is associated with significantly longer operative times as compared with primary pyeloplasties, especially during the exposure of the UPJ, but it is overall a safe and effective surgical modality for persistent/recurrent UPJO in children. As surgeons are increasingly asked for more accurate predictions of operative time lengths when scheduling cases, this information can be helpful for surgeons when scheduling these cases and with counseling families.