Immune thrombocytopenic purpura (ITP) is an organ-specific autoimmune disorder in which platelets opsonized by antiplatelet antibodies are destroyed by the reticuloendothelial system. As a result the peripheral blood platelet count is low; if sufficiently severe, it may lead to bruising and mucocutaneous bleeding. The disorder may occur in adults and in children; in the former the disease affects primarily females, whereas the childhood type affects the sexes equally. For most individuals the disorder is minor, requiring little treatment, but patients with more severe forms of the disease require therapy to elevate the platelet count to a safe level to prevent serious bleeding. Therapies include corticosteroids, intravenous immunoglobulin, splenectomy, and immunosuppressive agents. Because there have been few trials in ITP, there is little evidence to guide treatment, and all the treatments may have adverse effects in terms of morbidity and mortality. The American Society of Hematology and British Committee for Standards in Haematology guidelines provide a framework for management but nonetheless are based on little evidence. In this paper the authors review the management of ITP in adults, children, and pregnant women and highlight some of the novel therapies being explored in this disorder, in addition to some of the ongoing laboratory research exploring the mechanisms underlying the disease.