AbstractEighty‐five patients with acute myeloblastic leukemia (AML) presenting with hyperleukocytosis (HL) were analyzed to assess morbidity and mortality in early induction. Patients who failed to achieve remission were older and more often had pulmonary leukostasis (62% vs 23%, p = .01) and hepatomegaly (54% vs 31%, p = .06) at presentation. Thirty‐seven patients (44%) did not achieve complete remission (CR); 17 (54%) died early in induction therapy, 11 directly as a result of pulmonary hemorrhage with respiratory failure, while 5 had both pulmonary hemorrhage with respiratory failure and CNS hemorrhage. Early death patients were older and more often had pulmonary leukostasis (88% vs 29%, p<.0001), hepatomegaly (71% vs 34%, p = .01), hyperbilirubinemia (60% vs 16%, p = .01) and hypofibrinogenemia (47% vs 12%, p<.01) at presentation. Primarily for technical reasons, preinduction leukapheresis was not employed as often in this very‐high‐risk group as in other patients (56% vs 82%, respectively). Thus, sufficient heterogeneity exists in patients presenting with HL to define a subset of patients at particularly high risk for early mortality. Preinduction leukapheresis applied in a prospective controlled fashion should be evaluated to assess if such treatment may decrease early mortality in thi