Twenty patients with extensive thermal injury were entered into a prospective randomized double-blind trial of prophylactic intravenous immunoglobulin administration. Ten patients received intravenous immunoglobulin and ten, albumin controls. No statistically significant difference was found between mortality rates, mortality rates from sepsis, the incidence of positive blood cultures, the positive quantitative wound biopsies, urine cultures, or positive intravenous line cultures. No significant improvement was noted in assays of neutrophil chemotactic index or intracellular kill, assays of lymphocyte function, or helper/suppressor ratio. We did, however, note significant improvement in the incidence of polymicrobial blood cultures, cytomegalovirus titers, and blood endotoxin concentration in treated patients. While the high incidence of inhalation injury (16 out of 20 patients) and, therefore, the disproportionately high mortality rate (40% overall) in the study group do not permit extension of these observations to the burn patient population at large, certain cautious recommendations may be made with regard to the use of intravenous immunoglobulin G in the management of burn patients.