There is considerable contemporary interest in ventricular repolarization, since prolonged repolarization, especially when heterogeneous, is associated with ventricular tachyarrhythmias, syncope and sudden death. Delayed ventricular repolarization occurs as a congenital anomaly or may be acquired, for example because of the effect of medications on repolarizing currents. Many drugs have such actions and their effects are more often seen in patients made vulnerable by co-existent genetic abnormality, acquired heart disease such as heart failure and hypertrophy or electrolyte and metabolic problems. This brief review explores this problem.