This chapter focuses on the various etiologies for intracerebral hemorrhage (CH), ischemic stroke (IS), transient ischemic attack (TIA), and cerebral venous sinus thrombosis (CVST) that are caused by blood disorders. Bleeding disorders may be inherited or acquired. They include thrombocytopenia and platelet function disorders, coagulation factor deficiencies, excessive anticoagulation and hemorrhagic complications after thrombolysis. Blood disorders associated with myeloproliferative diseases and disseminated intravascular coagulation (DIC) can cause both bleeding and thrombosis. Heparin-induced thrombocytopenia (HIT), the anti-phospholipid antibody syndrome, and thrombotic thrombocytopenic purpura (TTP) are conditions that cause thrombocytopenia but are more frequently responsible for thrombosis than for bleeding. Blood transfusion therapy is recommended as the most important intervention for primary stroke prevention and secondary stroke prevention in children with sickle cell disease. Cytoreduction with hydroxyurea reduces the incidence of thrombosis in essential thrombocythemia, and aspirin reduces the incidence of thrombotic events in polycythemia vera.