Dystonia is a movement disorder characterized by sustained muscle tone. Antipsychotic agents sometimes cause acute dystonia that can rapidly worsen within a few hours or days. Because healthy children rarely receive antipsychotic agents, it is unusual to see antipsychotic agent-induced dystonia in pediatric emergency departments. We report a rare case of a 12-year-old healthy boy who presented with acute dystonia after administration of haloperidol for sedation. He was suspected of laryngeal dystonia because stridor and desaturation were present. The symptoms disappeared with the administration of hydroxyzine. Rapid diagnosis was important in this case because laryngeal dystonia is a potential life-threatening complication due to upper airway obstruction. Considering the risk of side effects, doctors who are not accustomed to administering pediatric anesthesia should consult a pediatrician and/or an anesthesiologist prior to administration of anesthetics to pediatric patients.