Hemostasis is the balance between bleeding and clotting and includes coagulation and fibrinolysis with platelet interactions. Despite developmental hemostasis that describes the major differences between neonates and older children and adults, neonates do not have increased bleeding or clotting unless clinical situations disturb the “balance.” Perinatal asphyxia alters the balance of hemostasis, resulting in abnormalities that may result in bleeding and thrombosis. The following discussion will describe normal hemostasis, laboratory measures of hemostasis, developmental hemostasis, and the effects of asphyxia on hemostasis.