Some patients with Guillain-Barré syndrome (GBS) develop bulbar palsy, which may lead to serious complications during the acute phase of the illness. A serological marker that could predict the occurrence of bulbar palsy would be valuable for the treatment of acute GBS. We examined the serum levels of various IgG antiganglioside antibodies in the sera of 16 patients with GBS with bulbar palsy [GBS-BP(+)] and 72 patients with GBS without bulbar palsy [GBS-BP(-)]. Anti-GT1a antibodies were detected in a higher percentage of the GBS-BP(+) patients (10/16, 63%) than the GBS-BP(-) patients (2/72, 3%). In addition to GT1a, a new disialosylganglioside antigen was recognized by the sera of four GBS-BP(+) patients. Anti-GM1b antibodies were also frequently detected in the sera of the GBS-BP(+) cases. However, anti-GM1 and anti-GalNAc-GD1a antibodies, which are highly associated with acute axonal motor neuropathy (AMAN), were not detected in any of the GBS-BP(+) cases, while anti-GM1 antibodies were detected in 29% (21/72) and anti-GalNAc-GD1a antibodies were detected in 8% (6/72) of the GBS-BP(-) cases. These findings suggest that the presence of particular antiganglioside antibodies might be related with certain clinical manifestations of GBS. In patients who are diagnosed with GBS, the presence or absence of anti-GT1a and anti-GM1b antibodies should be tested at the early stage of GBS so that appropriate therapies that prevent the development of bulbar palsy and improve the outcome of GBS, may be initiated.