The incidence of thrombosis is higher among newborn infants than in any other stage of pediatric development. This fact is the consequence of labile characteristics of the neonatal hemostatic system, in addition to exposure to multiple risk factors and the wide use of vascular catheters. Venous thromboses, which mainly affect the limbs, the right atrium and renal veins, are more frequently seen than arterial thromboses. A stroke may be caused by the occlusion of the arterial flow entering the brain or by occlusion of its venous drainage system. Purpura fulminans is a very severe condition that should be treated as a medical emergency, and is secondary to severe protein C deficiency or, less frequently, protein S or antithrombin deficiency. Most thrombotic events should be managed with antithrombotic therapy, which is done with unfractionated and/or low molecular weight heparins. Purpura fulminans requires protein C replacement and/or fresh frozen plasma infusion. Thrombolytic therapy is done using tissue plasminogen activator and should only be used for life-, or limb-, or organ-threatening thrombosis.