The aim of this meta-analysis was to evaluate the clinical outcomes and risks of anterior cruciate ligament (ACL) surgery in children and adolescents. We electronically searched Medline, the Cochrane Controlled Trial Database, Embase, and Medpilot for studies on surgical treatment for ACL ruptures in skeletally immature patients. We extracted baseline demographics, follow-up intervals, surgical details (i.e., ligament suture or reconstruction, physeal-sparing or transphyseal techniques, type of transplant, and methods of fixation). Endpoints comprised rates of growth disturbances and reruptures, as well as knee function (measured by the International Knee Documentation Committee's documentation system and the Lysholm score). Unweighted overall effect sizes (risks, risk ratios [RRs], and means of functional scores) were estimated by use of crude nominators and denominators, and random-effects meta-regression analysis was used for weighted data synthesis. A total of 55 articles reporting on 935 patients (median age, 13 years; range, 1.5 to 16 years) were suitable for the study. After a median follow-up of 40 months (range, 14 to 89 months), the weighted rate of leg-length differences or axis deviations was 1.8% (95% confidence interval [CI], 0% to 3.9%] and that of reruptures was 4.8% (95% CI, 2.9% to 6.7%). Excellent or good function (International Knee Documentation Committee grade A or B) was achieved in 84.2% (95% CI, 75.8% to 92.6%) of all knees, and Lysholm scores averaged 96.3 (95% CI, 95.5 to 97.2). Transphyseal reconstruction was associated with a significantly lower risk of leg-length differences or axis deviations compared with physeal-sparing techniques (1.9% v 5.8%; RR, 0.34; 95% CI, 0.14 to 0.81) but had a higher risk of rerupture (4.2% v 1.4%; RR, 2.91; 95% CI, 0.70 to 12.12). Sutures did not result in any growth disturbances, with a weighted rerupture rate of 4.6% (95% CI, 2.6 to 6.7). Fixation far from the joint line fared better than close fixation with regard to this endpoint (1.4% v 3.2%; RR, 0.42; 95% CI, 0.09 to 1.93). Bone-patellar tendon-bone grafts, which are also less likely to fail, were associated with higher risks of leg-length differences or axis deviations than were hamstrings (3.6% v 2.0%; RR, 1.82; 95% CI, 0.66 to 5.03). Meta-regression did not show a significant impact of the publication year on event rates. This meta-analysis showed low rates of leg-length differences or axis deviations and graft failures after ACL reconstruction in skeletally immature patients. Hamstring transplants may lower the risk of leg-length differences or axis deviations, and physeal-sparing techniques may increase the risk. Randomized controlled trials are needed to clarify important issues in managing ACL ruptures in children and adolescents. Level IV, meta-analysis of case series. Copyright © 2010 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.