Idiopathic thrombocytopenic purpura (ITP) is a primary immune thrombocytopenia that is typically manifested in adults by acute bleeding, severe thrombocytopenia, and normal to increased megakaryocytes in the bone marrow. Labeling studies suggest that most patients with ITP have an IgG antibody directed against the platelet membrane resulting in sequestration in the spleen, and that sequestration in other organs such as the liver bodes a poor prognosis. Splenectomy and/or corticosteroids remain the mainstay of therapy, with permanent remissions induced in 75% of patients. We review alternative forms of therapy such as immunosuppressive agents, high-dose gamma-globulin, and others to enable the practicing physician to select the best treatment for patients refractory to standard therapy. Age appears to influence response to therapy and morbidity, with advancing age imparting a poorer prognosis.