Infants and young children cannot describe symptoms of cardiogenic syncope accurately. If the attention in such cases is focused on the seizure activity that may follow, the patient will be treated inappropriately with anticonvulsants. We report such a presentation in 4 infants and young children (ages 6 to 48 months) with idiopathic long QT syndrome. All patients presented with recurrent seizures. All patients had a corrected QT interval (QTc) > or = 0.44 s and none had deafness. The diagnosis was suspected by careful history-taking which revealed episodes of loss of consciousness before convulsions in all patients. All patients were treated successfully with propranolol and remained free of symptoms during the follow-up period of 1-2 years. Screening the other family members revealed a prolonged QTc in 9 out of 16, and a history of 3 sudden and unexplained deaths in two families.