Therapeutic approaches for autoimmune diseases are primarily based on suppressive measures that down regulate an over productive immune system. The increasing availability of modern biological therapies has advanced the ability to target and to neutralize essential components of the immune response without experiencing the hazardous adverse effects caused by the traditional immunosuppressants. One of the noticeable examples of this approach is the increasing use of high-dose intravenous immunoglobulin (IVIg). IVIg mechanisms include modulating function of Fc receptors, interference with complement activation and cytokine network, provision of anti-idiotypic antibodies, regulation of cell growth, and effects on of T and B cells. In this review we gather existing information regarding IVIg mechanisms of action, clinical applications and its effects on various conditions.