The association of Q-T interval prolongation, syncope and sudden death is known as the long Q-T syndrome. The syndrome may be familial, associated with congenital deafness, or idiopathic. The diagnosis is based on the electrocardiographic finding of a prolonged Q-T interval with or without T wave abnormalities. In this article, we present a nine-year-old boy admitted to the Hacettepe University Children's Hospital with complaints of syncopal episodes. The prolonged Q-T syndrome was diagnosed as the cause of the syncopal attacks. In addition, the same syndrome was detected in his father. The prolonged Q-T syndrome should be considered in the differential diagnosis of cases with recurrent, unexplained syncope in the pediatric age group.