This work intends to be a review of the recent histopathological findings elicited by research into sudden and unexpected perinatal death and sudden infant death syndrome (SIDS) that have dictated a novel approach to the inherent problems by pathologists, especially those entrusted with forensic medical authority. The new approach stems from the recent advances made in the understanding of neuro- and/or cardiac-conduction-system diseases present in unexpected perinatal death and SIDS. These demand that an accurate morphologic examination be performed of these structures, which modulate respiratory, cardiovascular, digestive, and arousal activities, in all victims of sudden death. A histopathologic study of an ample register of cases of victims of sudden death, either perinatally or in early infancy, has demonstrated frequent alterations both of the autonomic nervous system (especially hypoplasia of the arcuate nucleus) and of the cardiac conduction system (accessory atrioventricular pathways). The present research provides an in-depth study of the many still-controversial aspects underlying perinatal unexpected death and SIDS and is recommended for professionals working in the forensic field, whose greater insight into this problem will allow more complete medicolegal documentation.