The recognition of ventricular repolarization abnormalities in the newborn carries several and significant implications, because it calls attention to the possibility of dealing with an infant affected by the long QT syndrome (LQTS). This article provides key elements for the correct measurement of the QT interval in newborns and succinctly reviews some aspects of the disease. It gives normative values on the QT interval distribution in the first month of life based on a prospective study in more than 44,000 infants. It shows the probability, based on the QTc observed in two recordings, to find disease-causing mutations. The data indicate clearly that widespread electrocardiographic screening in the newborn allows early identification of most, if not all, the infants affected by LQTS with marked QT prolongation and thus of those at higher risk for life-threatening arrhythmias and sudden death. Through the affected infants, it becomes possible to identify the family members affected by LQTS, including the "silent mutation carriers"; our study shows that disease-causing mutations are found in 51% of the family members. Because early recognition leads to the implementation of effective preventive strategies, it follows that electrocardiographic screening will avoid preventable deaths either in the first year of life when they are usually labeled as "sudden infant death syndrome" or later in life. The case is made for medicolegal implications whenever neonatologists and pediatricians fail to inform the parents of a newborn child of the prevalence of LQTS (one in 2000), of the effectiveness of existing therapies, and of the diagnosis with a simple electrocardiogram.