Effective treatment and prevention strategies for childhood stroke and porencephaly can only be developed once the causes are understood. There is increasing evidence that inherited and acquired coagulation abnormalities, alone or in combination with environmental factors, predispose to arterial and venous thrombosis. Inherited abnormalities of factor V leiden, prothrombin, protein C, protein S, and antithrombin III may account for many of these thromboses. At present there is little information on the existing distribution of these coagulation anomalies in children with thrombosis. Recent reports suggest that these clotting abnormalities may be responsible for some instances of intracranial hemorrhage, porencephaly, cerebral palsy and fetal death.