Human intravenous immunoglobulin (hIVIG) is a preparation of normal polyspecific IgG obtained from the plasma of healthy blood donors. Although purified immunoglobulins were initially developed for treatment of primary immunodeficiency syndromes, they have since been documented to be effective in the treatment of some immune-mediated diseases such as immune-mediated thrombocytopenia purpura and autoimmune hemolytic anemia. Blockade of Fc receptors on mononuclear phagocytic cells has been proposed as the most likely mechanism for the rapid early response to hIVIG treatment. Human IVIG has been used to treat canine immune-mediated hemolytic anemia (IMHA), anemia with myelofibrosis, and immune-mediated thrombocytopenia. Doses from 0.5 to 1.5 g/kg may be effective, although most studies have used a dose of 1 g/kg. Human IVIG is administered as an intravenous infusion over 6 to 12 hours, and dogs should be carefully monitored for adverse reactions during administration. The possibility of a increased risk of thromboembolism should be considered when undertaking hIVIG treatment. The safety of multiple treatments of hIVIG has not been established. In most dogs with IMHA, benefit may be limited to short-term improvement in hematocrit, which may allow time for other treatment modalities to become effective. Dogs with nonregenerative anemia and associated myelofibrosis may have longer-term responses to hIVIG treatment.