BACKGROUND Extrahepatic portal vein obstruction (EHPVO) has been associated with growth impairment in children. We hypothesized that growth parameters improve after reversal of portal hypertension and restoration of mesenteric venous blood flow to the liver by the mesenterico-left portal vein bypass (MLPVB). METHODS A retrospective review of 45 children with idiopathic EHPVO who underwent MLPVB between 1997 and 2007 and had follow-up data for analysis was carried out. Growth was assessed using SD scores (z scores) for height, weight, and body mass index (BMI) at the time of operation and at early (5-12 months) and late (13-24 months) follow-up. RESULTS The mean height and weight of children with EHPVO was significantly lower than the general population before surgery. Mean BMI was also lower, although statistically insignificant. All parameters increased significantly after MLPVB as follows: height from -0.42 before surgery to -0.12 (P = .027) at 5 to 12 months and -0.14 (P = .026) at 13 to 24 months; weight from -0.49 before surgery to 0.03 (P < .001) at 5 to 12 months and 0.35 (P < .001) at 13 to 24 months; and BMI from -0.22 before surgery to 0.17 (P = .001) at 5 to 12 months and 0.48 (P < .001) at 13 to 24 months. CONCLUSIONS Restoration of portal blood flow to the liver by MLPVB improves growth in children with EHPVO.