There is an association between the presence of antibodies that bind to anionic phospholipids and the occurrence of repeated spontaneous abortion. Many uncontrolled studies have reported favorable pregnancy outcome in women treated with steroids, low-dose aspirin, heparin, or their combination. Similarly, treatment failures have been reported with most of these therapeutic regimens. Immunoglobulins play a central role in immune regulation. A wide spectrum of human diseases are associated with decreased or abnormal regulation of Ig levels. Recently, IV preparations of Ig have become available for clinical use, including treatment of patients with recurrent abortions and high levels of antiphospholipid antibodies. 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. Determination of dosage of IV Ig, duration of treatment, and treatment intervals are all empirical in patients with recurrent abortions and high levels of antiphospholipid antibodies because antiphospholipid antibody levels are not useful for monitoring therapy. Although the data available at present are promising, additional randomized trials are needed to determine the efficacy of IV Ig in patients with immunological recurrent abortions.