The successful treatment of hematological malignancies remains challenging. Prognosis is often dismal given the frequency of disease relapse or treatment refractory disease. Cytotoxic and cytostatic chemotherapy remain mainstream therapeutics for most hematological malignancies. However, improved understanding of tumor immunobiology is providing appealing anti-cancer strategies targeting selected component of immune response. Since approval of rituximab for treating B cell malignancies in 1997, availability of monoclonal antibodies against tumor specific surface molecules has driven the development of the emerging field of cancer immunotherapy. This strategy of modulating the immune response is taking an increasingly prominent role in the treatment of hematological malignancies with several new antibody-based therapeutics becoming available for patients with leukemia/lymphoma. In addition, with an increasingly appreciated role for T cell immunity in cancer pathogenesis, strategies enhancing T cell activation as well as inhibiting T cell suppression mechanisms are under active development. Therapeutic vaccines to improve efficacy of antigen processing and presentation, agonists for co-stimulatory molecules, adoptive transfer of genetically-modified T cells, as well as agents that suppress negative regulatory pathways for T cell function are all under active clinical investigation. Although most of these studies are in early stages, preliminary data are very promising. Availability of additional immune-based therapeutic options for patients with hematological malignancies is anticipated in the near future.