Syncope and presyncope are symptoms that occur infrequently in children, are unpredictable, and represent a diagnostic challenge to the physician.Conventional diagnostic investigations are often unable to establish a diagnosis, making it difficult to determine patient risk and direct appropriate therapy.The implantable loop recorder (ILR) is a medical device that was created for prolonged monitoring of heart rate and rhythm and has been used in a limited number of pediatric studies in which the cause of the syncope is unknown.Methods:This is a retrospective review of the clinical, surgical, and follow-up data o f patients who had ILR devices implanted after conventional testing failed to identify a cause for their symptoms.Results:The diagnostic yield of the ILR device in unmasking the cause for symptoms in our patient cohort was 64%.In our study, manually activated events accounted for 71% of all documented episodes and 68% of the cases involving hemodynamically important arrhythmias or transient rhythm changes.The ILR device can be safely implanted and explanted in children without significant morbidity, in most cases.None of our patients experienced any long-term adverse events associated with placement of the device and all were alive at last follow-up.Conclusions: The use of the ILR device is a useful tool to help unmask arrhythmias as a cause of unexplained syncope in children.Patient selection for who should and should not have an ILR device implanted will continue to influence its diagnostic utility and generate controversy among stakeholders.