Isolated T wave alternans (repolarization alternans) is frequently associated with long QT syndrome. However, electrical alternans involving the P wave, QRS complex, ST segment (depolarization alternans), and the T wave is a rare finding. This report describes a 62-year-old woman with long QT syndrome and an electrical alternans occurring after previous syncope. Alternating QRS complexes showed a prolonged PR interval, a Brugada syndrome resembling pattern of the QRS complexes (elevation and downslope of the ST segments), and a T wave alternans. A genetic basis for the long QT syndrome has been ruled out by sequencing of all coding areas of the LQT genes. Potential mechanisms for the electrical alternans are discussed.