To determine whether warm-antibody autoimmune hemolytic anemia (AIHA) responds to treatment with intravenous gammaglobulin (IVGG), we conducted separate pilot studies at three institutions enrolling a total of 37 patients. We combined these results with a review of 36 cases of AIHA treated with IVGG reported in the literature. Sixteen clinical variables were examined to determine associations with response to IVGG. Overall, 29 of 73 patients (39.7%) responded to IVGG therapy. Two variables were strongly related to a good response to IVIG: the presence of hepatomegaly (with and without splenomegaly) and a low pre-treatment hemoglobin. A trend towards a better response was observed in the 11 children. Overall, IVGG provided acute benefit in only 1/3 of patients and therefore cannot be recommended as standard therapy for AIHA. It may, however, be useful as adjunctive treatment in selected cases, such as in those with a pre-treatment hemoglobin < 6-7 gm/dl or those with hepatomegaly, and in clinical settings where the toxicity of other treatments may be an important consideration.