Electrical instability of the heart has numerous congenital origins. This review approaches the problems from a morphological standpoint, utilizing selected examples from my own studies of the human cardiac conduction system performed during the last three decades. Subjects discussed include multifocal Purkinje cell tumors, benign congenital polycystic tumors of the AV node, several types of congenital heart block, postnatal morphogenesis of the AV node and His bundle (including considerations of persistent fetal dispersion and crib death), the Wolff-Parkinson-White syndrome, left superior vena cava, focal fibromuscular dysplasia of small coronary arteries, hereditary neuromuscular or musculoskeletal diseases, familial atrial fibrillation, long QT syndrome, and apoptosis of the heart. In many congenital disorders of cardiac electrical activity, both arrhythmias and conduction disturbances may occur. How the abnormal anatomy may relate to cardiac electrical instability is discussed, including certain clinical matters to be considered.