Treatment of acute Guillain-Barre syndrome (GBS) comprises the best standard of intensive care on one hand and immunomodulatory treatments on the other. Two multicenter trials have established the value of plasma exchange therapy to shorten the clinical course of acute GBS. A further study revealed equal results with plasma exchange and intravenous immunoglobulin (IvIG) treatment. The mode of action of IvIG is unknown, the effect may be in part due to HLA-and CD-4-molecules contained in variable concentrations in the various preparations. Since the preparation procedures vary considerably, one cannot a priori assume equal efficacy of all products. Treatment by IvIG offers numerous logistic and technical advantages, however, a number of adverse effects in the form of myocardial infarction, stroke, renal failure, and hepatitis C infections have been reported. The current multicenter trials on the treatment of acute GBS will provide more detailed information on the value of IvIG treatment.