Abstract. The results of high-dose intravenous gammaglobulin therapy (IVGG) of adults with immune thrombocytopenic purpura (ITP) were reviewed in 28 published reports which included 282 patients. Overall, 64% of the patients responded to IVGG with a peak platelet count greater than 100,000/mm3; 83% had peak platelet counts greater than 50,000/mm3. Unmodified immunoglobulin was superior to modified immunoglobulin; 70% of the patients treated with the former having platelet increases to >100,000/mm3 compared to only 49% of those treated with the latter. More patients were refractory among those who had had ITP for at least 3 years. A higher peak platelet count immediately after IVGG administration was correlated with a longer duration of the platelet response. Patients above the age of 60 tended to have a weaker response to IVGG than did younger patients, and females tended to respond better than males. A pre-IVGG platelet count of >10,000/mm3 was not associated with a poor response to IVGG. While there is still no way to reliably predict response prior to therapy in an individual patient, the above information may help in the decision of whether or not treatment with IVGG is likely to be successful. It also suggests that inhibition of antiplatelet antibody production is an important mechanism of IVGG effect at least in some patients.