We present a multicenter validation of a modified Manchester Triage System (MTS) flowchart for pediatric patients who present with headache to the emergency department. A prospective observational study was conducted across 5 European pediatric emergency departments. The standard MTS headache flowchart and a modified MTS headache flowchart were tested in the participating centers, and results were compared with triage categories identified by either the physician at the end of the clinical examination or the reference classification matrix (RCM). Fifty-three patients were enrolled in the preimplementation phase and 112 in the postimplementation phase. When compared with physician's triage and RCM, the modified MTS flowchart demonstrated good sensitivity (79% and 70%, respectively), specificity (77% and 76%, respectively), and a high positive likelihood ratio (9.14 and 16.75, respectively) for the identification of low-risk children. Conclusions: Our modified headache flowchart is safe and reliable in pediatric emergency settings, especially for lower classes of urgency.