PURPOSE: To ascertain the activity of intravenous immunoglobulin in a wide range of diseases. DATA IDENTIFICATION: English-language literature search using MEDLINE (1982 to 89), review of meeting reports, and extensive hand searching of bibliographies of identified articles. STUDY SELECTION: All identified articles. DATA EXTRACTION: Study quality and specific descriptive information concerning population, intervention, and outcome measurements were assessed. RESULTS of DATA SYNTHESIS: There have been few controlled, randomized trials of intravenous immunoglobulin. Available data suggest efficacy in persons with primary immune deficiency, premature infants at risk for group B streptococcus infection, patients with Kawasaki disease, transplant recipients at risk for cytomegalovirus infection, patients with idiopathic thrombocytopenic purpura, and selected patients with chronic lymphocytic leukemia. Data are also favorable concerning the use of intravenous immunoglobulin in some other autoimmune disorders, but randomized trials are needed. Interesting areas for future study include the acquired immunodeficiency syndrome (AIDS), multiple myeloma, and lymphomas. Risks of intravenous immunoglobulin are minimal. CONCLUSION: Intravenous immunoglobulin is safe and effective in treating several human diseases. Additional randomized trials are needed.