Intracerebral hemorrhage (ICH) contributes significantly to the morbidity and mortality of patients suffering from acute leukemia. While ICH is often identified in autopsy studies of leukemic patients, it is rare for ICH to be the presenting sign that ultimately leads to the diagnosis of leukemia. We report a patient with previously undiagnosed acute precursor B-cell lymphoblastic leukemia (ALL) who presented with diffuse encephalopathy due to ICH in the setting of an acute blast crisis. The diagnosis of ALL was initially suspected, because of the hyperleukocytosis observed on presentation, then confirmed with a bone marrow biopsy and flow cytometry study of the peripheral blood. Furthermore, detection of the BCR/ABL Philadelphia translocation t(922)(q34q11) in this leukemic patient by fluorescent in situ hybridization permitted targeted therapy of the blast crisis with imatinib (Gleevec). Understanding the underlying etiology of ICH is pivotal in its management. This case demonstrates that the presence of hyperleukocytosis in a patient with intracerebral hemorrhage should raise clinical suspicion for acute leukemia as the cause of the ICH.