The ventricular gradient concept of Wilson was an important insight into the physiology of ventricular repolarization and its electrocardiographic expression. For many years the validity of the concept was questioned because QRST deflection area was not independent of ventricular activation sequence but it is now evident that electrotonic effects on repolarization account for that behavior. There is solid theoretic and experimental evidence that QRST deflection area depends on disparity of repolarization. The established relation of disparate repolarization to arrhythmia vulnerability provides an important clinical objective for measurement of the QRST area and promising evidence for the prediction of arrhythmias has been obtained. Finally, there is evidence that the sufficiently sampled map of QRST deflection areas provides useful information concerning the distribution of repolarization properties as well as their disparity.