Many idiopathic epilepsies have been shown to be caused by ion channel dysfunction. Channelopathies also cause the long QT syndrome (LQTS) which is associated with syncopes and sudden cardiac death. It has been postulated that the same channelopathy may be associated with both epilepsy and LQTS. We report a patient with idiopathic epilepsy who died in sudden unexpected death in epilepsy (SUDEP) at the age of 25. A post mortem DNA sequencing of the LQTS-associated genes revealed a novel missense mutation in the SCN5A gene coding for the cardiac sodium channel, voltage gated, type V, alpha subunit. The possibility that the mutation may explain both the epilepsy and the sudden death is discussed. However, the patient was treated with lamotrigine which may interfere with cardiac ion channels and may also have played a part in inducing a terminal cardiac arrhythmia.