The management of thrombosis in patients with cancer is a clinical challenge. Although the prevalence of thromboembolic complications in hematologic malignancies is lower than that reported for solid tumors, thrombotic events are increasingly being reported both in patients with acute leukemia and in those with chronic myeloproliferative and lymphoproliferative disorders. Accordingly, there is the need for promptly identifying patients at a higher risk of developing thromboembolic complications, as well as instituting appropriate measures of prophylaxis and treatment. We briefly summarize the pathogenetic evidence for the existence of a prothrombotic state in patients with hematologic malignancies, discuss common clinical pictures, and examine those modalities of prophylaxis and treatment that are commonly recommended in this clinical setting. Further work is needed to provide physicians with specific guidelines for a systematic management of thrombosis in patients with hematologic malignancies.