Intravenous immunoglobulin therapy does not appear to be efficacious in the prevention of neonatal sepsis. The value of a 3-4 percent reduction in sepsis or any serious infection without a reduction in mortality must be weighed against the cost of the therapy. The efficacy of IVIG therapy in the treatment of neonatal sepsis remains uncertain. The results of the ongoing International Neonatal Immunotherapy Study should provide definitive answers regarding the effectiveness of this therapy. Long-term follow-up and cost (length of stay) are important components of this study. Ohlsson and Lacy recommend studies evaluating the effectiveness of IVIG preparations with high concentrations of antibodies to common unit- or geography-specific pathogens. The cost-effectiveness of the production and use of such products should be included in study designs. Part IV of this series will explore the use of the amino acid glutamine as an immunomodulating agent in neonates.