Hemorrhagic infarction of the basal ganglia was observed in 2 young adult patients with acute leukemia who presented with progressive hemiparesis combined with severe mental alterations. In case 1 (acute myeloblastic leukemia) lethal infarction due to thrombosis of both internal cerebral veins occurred during induction therapy for relapsed leukemia; in case 2 (common acute lymphoblastic leukemia) a devastating stroke probably due to deep cerebral venous thrombosis happened during the 3rd remission. Neither of them had hyperleukocytosis, signs of infection, disseminated intravascular coagulation or CNS leukemia. Long-term glucocorticoid therapy (case 1) and combined prophylactic CNS treatment (case 2) were discussed as possible risk factors for cerebrovascular thrombosis in acute leukemia.