Guillain-Barré syndrome (GBS) is an acute self-limited motor-dominant neuropathy, in which autonomic nervous system is frequently involved. Cardiovascular complications, such as hypertension, hypotension, bradyarrhythmias, and tachyarrythmias, are particularly important because they are sometimes life-threatening. Antiganglioside antibodies are frequently present in the acute-phase sera of GBS. They are considered to be useful for diagnosis and to be involved in the pathogenetic mechanisms. No association between autonomic dysfunction and antiganglioside antibody however has been reported. Recently, we performed the quantitative sudomotor axon reflex test (QSART) in GBS patients and found that patients with high scores in QSART had anti-GQ1b IgG antibodies. It indicates the association between postganglionic sudomotor dysfunction and anti-GQ1b antibodies. Further investigation on larger number of patients is needed to clarify the role of antiganglioside antibodies in the development of autonomic dysfunction.