The introduction of preparations of immune serum globulin that are safe for intravenous use (IVIG) has made possible safe and effective prophylactic treatment for patients with a variety of humoral immunodeficiencies. These include not only primary agammaglobulinemia and common variable hypogammaglobulinemia but also the antibody deficiencies that accompany chronic lymphocytic leukemia (CLL) and multiple myeloma, as well as the hypogamma-globulinemia found in very low birth weight newborns who have not received adequate transplacental IgG from their mothers. In contrast, trials to date have not shown efficacy of IVIG in preventing sepsis in burn patients. The ease of administration and efficacy of IVIG in preventing respiratory symptoms in hypogammaglobulinemic patients has suggested that many other patients presenting with sinusitis and asthma, recurrent bronchitis, and other chronic chest symptoms might also benefit from IVIG and that they should be worked up for IgG subclass or specific antibody deficiencies. Side effects of IVIG administration are generally minor and may be prevented by slow administration and/or pretreatment with aspirin or Benadryl. The only contraindication to IVIG treatment is anaphylactic sensitivity to IgA, which is extremely rare. IVIG is thus an effective and safe form of prophylaxis that can reduce the incidence of pneumonia and other respiratory infections in patients with antibody deficiency as a predisposing factor.