Intravenous immunoglobulin (IGIV) originally was used as prophylactic treatment of infections in patients with primary immunodeficiency disease. Today, administration of IGIV, due in large part to its immunomodulatory activity, has expanded to include a number of other disorders. Available data suggest that the accepted indications for IGIV will continue to expand. As the number of clinical applications for this therapy grows, so will market opportunities; current preparations will be modified and improved and new products introduced. Intravenous immunoglobulin therapy has improved the lives of many patients with immune-related disorders. Future applications will ideally advance this paradigm further.