Conventional doses of intravenous immunoglobulin (i.v. Ig) (0.4 g/kg/day for 5 days) commonly produce a remission in immune thrombocytopenia (ITP) but have only rarely been successful in autoimmune haemolytic anaemia (AIHA). There are a few reports of higher doses of i.v. Ig being more effective in AIHA. We have treated two patients with AIHA with high-dose i.v. Ig (0.5 g/kg/day for 5 days). In one patient with an associated ITP a prompt rise in platelet count but no change in Hb concentration occurred. The second patient with AIHA associated with chronic lymphatic leukaemia showed a prompt response, with a rise in Hb concentration and fall in plasma bilirubin. The poor response to i.v. Ig seen in AIHA may be related to the expansion of the reticulo-endothelial system seen in AIHA but not ITP. Clearance of antibody-coated red cells and platelets may occur at different rates and/or sites in the reticulo-endothelial system and this may account for the differential response seen in case 1. Higher doses of i.v. Ig, in the range 0.5-1 g/kg/day for 5 days, are required in AIHA, particularly if significant splenomegaly is present, and may be effective in refractory cases.