Conjunctival and facial petechiae have been regarded as classic signs of asphyxial death. First described by Tardieu in the 19th century, external and visceral petechiae have since been interpreted as hypoxia-related sequelae of asphyxia, sometimes being attributed in part to "mechanical obstruction of the upper air-way." Despite consensus in the literature that cephalic petechiae are not found in all asphyxial deaths, and that they are observed commonly in natural deaths without an asphyxial mechanism, the view that petechiae and asphyxia are causally linked continues to be perpetuated, without regard to the inherent inconsistencies central to that theory. Excluding those related to infectious, coagulopathic, or microembolic etiologies, the authors conclude that petechiae of the head are the product of purely mechanical vascular phenomena; namely, impaired or obstructed venous return in the presence of continued arterial input. As pressure builds in venules and capillaries, particularly those with little surrounding connective tissue support, such as the conjunctivae and eyelids, vascular rupture produces petechiae. The likelihood of this occurrence is directly proportional to the degree of venous obstruction and inversely proportional to that of arterial compression at or above the level of the heart. 33 references