Background And Aims: In this study, we assessed the association between preoperative hemoglobin and red blood cell transfusion in children undergoing spine surgery after the implementation of our preoperative iron supplementation protocol.Method: We performed a retrospective analysis of patients who underwent posterior spinal fusion surgery between January 2013 and December 2017 and received preoperative iron supplementation. We used uni- and multivariable logistic regression to determine the association between preoperative hemoglobin level and red blood cell transfusion in patients receiving iron supplementation.