Four patients with warm type autoimmune hemolytic anemia who failed to respond to steroid therapy received high dose intravenous gammaglobulin (0.2-0.4 g/kg daily) for five days. In one patient hemolysis occurred in association with non-Hodgkin's lymphoma and in the others the cause of the hemolysis was not established; two patients had prior splenectomy. A response to gammaglobulin therapy, demonstrable by a rise in or stabilisation of hemoglobin levels, a decrease in elevated serum bilirubin and lactate dehydrogenase levels, or prolongation of a shortened red cell (51Cr) survival, was observed in three patients. In two of these patients the effect of gammaglobulin therapy was temporary but allowed for splenectomy to proceed in one patient, without blood transfusion. The third patient continued to improve after cessation of gammaglobulin treatment. These findings suggest that high dose intravenous gammaglobulin may temporarily ameliorate hemolysis in some individuals with warm type immune hemolytic anemia, and may be a useful adjunct to steroids immediately before splenectomy.