Background: Cardiac conduction abnormalities are reported after ingestion of a toxic dose of carbamazepine. Case presentation: We describe the case of a four-year-old child with carbamazepine acute poisoning who developed reversible synoatrial block along with neurological toxic signs, despite a serum level of carbamazepine close to the upper limit of the therapeutic range. Discussion: Although carbamazepine-induced sinoatrial block has been reported in the literature even at therapeutic doses in adult patients, our personal research has not identified any record of this cardiac conduction abnormality in acute carbamazepine poisoning at pediatric age. Conclusion: The electrocardiogram is indispensable in the assessment and monitoring of pediatric cases with acute poisoning with carbamazepine.