The objective of the study was to evaluate the use of guidelines to determine the need of cardiac monitoring in children who sustained an electrical injury. The prospective use of guidelines since implementation July 1994 to June 1998 in a tertiary care pediatric teaching hospital was reviewed. Guidelines were cardiac monitoring for 24 hours is done on children with past cardiac history, loss of consciousness, voltage >240 volt or abnormal electrocardiogram (ECG); an ECG was obtained only when theoretical risk factors were present (tetany, decreased skin resistance by water or burns) or an unwitnessed event. Cardiac monitoring was performed in 29/224 (13%) patients (all normal) for 421 hours since implementation of the guidelines. Reasons included abnormal ECG (n = 10), voltage >240 volts (n = 6), lost of consciousness (n = 3), past cardiac history (n = 2), and unjustified (n = 9). There was no morbidity (0/172 patients 95% CI 0 to 1.7%) or mortality (0/224 patients 95% CI 0 to 1.3%). The guidelines were helpful in determining the need of cardiac monitoring in children after an electrical injury without any apparent risk.