The development of immunoglobulin preparations suitable for intravenous use that are safe, acceptable, and efficacious represents a major advance in the treatment of immunodeficient patients. Experience in the United States and elsewhere in the world indicates that the benefits of use in patients with well-documented humoral immunodeficiency far outweigh the risks of administration. As noted later in this issue (see "Report of the WHO Scientific Group: Primary Immunodeficiency Diseases"), "it may be considered as the treatment of choice for most immunodeficient patients requiring Ig replacement." By use of frequent infusions made logistically possible through the home infusion programs, serum levels can be maintained within the normal range. The reports of non-A non-B hepatitis make it prudent to monitor such patients (as with any patients receiving blood products) with serial liver function tests.