Our understanding of the pathophysiologic abnormalities contributing to pre-eclampsia has increased substantially over the past decade. This has been accompanied by the introduction of various methods which reduce the incidence of pre-eclampsia to approximately the same range (4-11.8% in high risk group), by attempting to correct the pathophysiologic abnormalities involved, rather than averting its occurrence. Numerous reports suggest that pre-eclampsia is caused by an abnormal maternal immune response to antigenic challenge by the fetoplacental allograft. If this assumption is true, it may be possible to manipulate the maternal immune response to fetal allograft and to assist the immunologic homeostasis of the maternal host with her conceptus by passive immunization with intravenous immunoglobulins (IVIg) and thus, to prevent pre-eclampsia. Recently IV preparations of Ig have become available for clinical use including treatment of various immunologic disorders during pregnancy. The effectiveness of this new mode of therapy can be related to several immunological mechanisms such as blockade of antibody binding to receptors on macrophages, increase in T suppressor cells, or decrease in antibody synthesis. The latter effect may be mediated by anti-idiotypic antibodies in the Ig preparation, which may bind to idiotypes on pathogenic autoantibodies and neutralise their activity.