The National Institutes of Health Consensus Development Conference on Intravenous Immunoglobulin: Prevention and Treatment of Disease brought together biomedical scientists in immunology, infectious disease, and pediatrics, as well as health care providers, patients and their families, and the public to address the safe and effective uses of intravenous immunoglobulin (IVIG) preparations. Following 1 1/2 days of presentations by experts and discussion by the audience, a consensus panel weighed the evidence and prepared a consensus statement. Among their findings, the panel concluded that all currently available IVIG preparations are safe and effective in treating the conditions for which they have been licensed; however, their efficacy in treating other conditions remains to be established. Effective regimens have been developed for primary immunodeficiencies and secondary immunodeficiencies, idiopathic thrombocytopenic purpura, and Kawasaki syndrome. However, optimal dosages and treatment schedules still need to be established for patients who may benefit from IVIG therapy. The panel also concluded that the risks of IVIG therapy are minimal, and adverse events, which are rare, can often be alleviated by reducing the rate or volume of infusion. Future research is also important, particularly studies to discern the mechanisms of action of IVIG, to compare the effectiveness of IVIG preparations, and to determine their long-term effectiveness and their effect on quality of life for patients receiving IVIG. The full text of the consensus panel's statement follows.