We compared intravenous immunoglobulin (IVIG) and plasma exchange (PLEX) in the treatment of 50 patients with Guillain-Barré syndrome (GBS). Standard outcome measures did not differ for the two groups. Sixty-one percent of the PLEX-treated group and 69% of the IVIG-treated group improved by one disability grade at 1 month. The complication rate was higher in the PLEX-treated group. We conclude that the efficacy of IVIG in the treatment of GBS is comparable with that of PLEX and that it can be used safely, although we had a small number of patients. We did not observe a higher relapse rate with IVIG. The usefulness of combination therapy is unknown at this time.