Objective: Specific protocols for anticoagulation for children on ECMO vary across institutions, with most using a continuous infusion of unfractionated heparin. The goal of this study is to aid clinician's decision on the best measure of heparin anticoagulation test; which would be the one that correlates well with heparin activity and helps in predicting hemorrhagic and thrombotic complications. Data sources: A comprehensive search of MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, and Scopus was conducted from each database's inception to 07/13/2018. Study selection: Studies evaluating children (<18 years)treated with ECMO and evaluating ACT, aPTT, TEG and Anti-Xa in any language were included. Data extraction: Two reviewers selected and appraised studies independently, and abstracted data. Results: We included 19 studies (759 patients, mean age 19.8 months). Meta-analysis showed strong correlation between heparin dosing and anti-Xa. Additionally, there was not a strong correlation between laboratory tests and complications (hemorrhagic and thrombosis), or mortality. Conclusion: Based on current evidence, Anti-Xa is the only laboratory test that shows strong correlation with heparin infusion dose and seems like the most suitable test for monitoring of anticoagulation with heparin in children on ECMO.