An earlier investigation from our laboratory (Ilyas AA, Wilson HJ, Quarles RH, et al. Serum antibodies to gangliosides in Guillain-Barré syndrome. Ann Neurol 1988;23:440-447) demonstrating the presence of high levels of antiganglioside ganglioside antibodies in the sera of 5 of 26 patients with Guillain-Barré Syndrome (GBS) but not in control sera is summarized. The ganglioside antigens varied among the 5 patients with positive findings, and the antiganglioside antibodies decreased concurrently with clinical improvement in those patients for whom longitudinal samples were available for analysis. The results are discussed in the context of antibodies to acidic glycolipids in other types of neuropathy and other studies on antiglycolipid antibodies in GBS. Data showing the occurrence of lower levels of antibodies to P2 protein, P0 glycoprotein, and myelin-associated glycoprotein in some of the GBS patients are also summarized. The findings from our laboratory combined with the results of others make it unlikely that antiganglioside antibodies have a notable pathogenic effect in most patients with GBS, but the possibility remains that they are of pathogenic importance in some patients with the highest antibody titers.