Syncope in children and adolescents is a common problem which almost always has a definable etiology. A search for the underlying diagnosis is important because of the risk of injury or sudden death. Such a search should include history, examination, laboratory screening, and ECG as a primary workup protocol. Such an evaluation can be done at relatively low cost and will establish the diagnosis in most cases. The most frequent cause in childhood is vasovagal syncope or other reflex mechanisms that usually require no ongoing care. If, however, a cardiac cause is found, the potential for an untoward outcome is greater, and, accordingly, diagnostic and treatment steps need to be thorough and comprehensive. If no etiology is found, particularly if the episodes are recurrent, extensive cardiac studies may be required, including inpatient electrophysiologic testing. A small percentage of children with heart block or intractable symptoms may ultimately require a pacemaker.