Persons with hematologic malignancies bleed for a variety of reasons, including alterations in platelet function and numbers, clotting factor deficiencies, circulating anticoagulants, and defects in vascular integrity. The management of bleeding begins with a full characterization of the hemostatic defect. Vitamin K deficiency always should be considered and excluded by clinical history and laboratory tests. Localized bleeding is treated by packing, topical hemostatic agents, dressings, vessel ligation, laser beam coagulation, or embolization. Platelet transfusions are administered for hemorrhage secondary to severe platelet dysfunction or thrombocytopenia, but usually are not indicated if there is no bleeding, even though platelets may be as low as 10,000/microL. Bleeding due to thrombocytopenia that is refractory to random-donor platelets may respond to cross-matched compatible platelets, or to recombinant factor VIIa (rFVIIa). Fresh frozen plasma is indicated infrequently; bleeding due to coagulopathies is better managed with cryoprecipitate if fibrinogen is low, or with clotting factor concentrates appropriate for the specific clotting factors found to be deficient. rFVIIa or activated prothrombin complex concentrate usually controls hemorrhage due to autoantibodies directed against factor VIII, and acquired von Willebrand's disease may be responsive to desmopressin or intravenous gamma globulin infusion. Antifibrinolytic agents often enhance other hemostatic therapies, but should be withheld if there is genitourinary bleeding or evidence of disseminated intravascular coagulation. Finally, plasmapheresis and immunoadsorption to remove paraproteins may be helpful when other measures fail to curb bleeding.