Background: Conventionally, an adult's standard of a 40-cm loop is adopted in Roux-Y hepatojejunostomy (RYHJ) in choledochal cyst (CDC) in children, irrespective of patient size. The redundant length of the jejunal limb may lead to complications. We compared the outcome of an individualized short Roux loop with the standard loop length in RYHJ in children with CDC. Methods: Two hundred eighteen children with CDC undergoing laparoscopic RYHJ were prospectively randomized into 2 groups: (1) conventional group (CG; n = 108) where a standard 35-40 cm Roux-loop length was used regardless of the child's size and (2) short loop group (SLG; n = 110) in which the Roux-loop length was based on the distance between hepatic hilum and umbilicus. Ultrasonography, upper gastrointestinal contrast studies, and laboratory tests were conducted during the follow-up period. Results: The mean Roux-loop length of SLG was significantly shorter than that of CG (Student t test, P < .05). There was no significant difference between the 2 groups in age, operative blood loss, operative time, postoperative hospital stay, and duration of drainage. In CG, 2 of (1.8%) 108 patients developed Roux-loop obstruction, whereas none was detected in SLG (0%). Mild reflux was detected in 2 CG patients and 1 SLG patient 1 month postoperatively, all of which subsided 6 months later. No episodes of cholangitis were observed in either group. Conclusions: An individualized short Roux-loop length in RYHJ is as effective as the conventional Roux-loop length. (C) 2010 Elsevier Inc. All rights reserved.