We report a rare case of Guillain-Barré syndrome (GBS) in a patient with anti-GT1a antibody. A 42-year-old man was admitted with dysphagia, dysarthria and weakness in his neck and both upper limbs. Serial electrophysiological studies suggested that the predominant process was demyelination of the motor nerves. Thin-layer chromatography with immunostaining revealed that his serum IgG reacted strongly with GT1a and weakly with GQ1b. He recovered rapidly with plasmapheresis. These findings suggest that anti-GT1a IgG antibody might play an important role in the pathogenesis of bulbar palsy in GBS.