Guillain-Barré syndrome (GBS) is a form of acute inflammatory (demyelinating) polyneuropathy. It causes rapidly ascending numbness and weakness. In the early phase, a high index of suspicion for GBS is essential in the presence of ascending numbness and weakness because ancillary tests may not help. A normal cerebrospinal fluid (CSF) protein level in the early phase or a finding of numerous lymphocytes does not exclude the diagnosis of GBS. By end of first week of illness, CSF analysis usually reveals normal CSF pressure and elevated protein without leukocytosis termed albuminocytological dissociation. Despite advances in the treatment of GBS, good supportive care is still the most important determinant of favorable outcome. Cardiac monitoring is routine for patients with severe findings. Respiratory status is assessed with periodic vital capacities. Elective endotracheal intubation for ventilatory support is considered when the vital capacity is below 15 ml/kg.