Guillain-Barré syndrome (GBS) is an acute demyelinating disorder of the peripheral nervous system that results in motor weakness, absent reflexes and autonomic nervous system dysfunction. Autonomic failure is reported in approximately 65 % of patients with GBS and usually follows extensive motor involvement. In this case our patient presented with syncope and other signs of autonomic failure before the motor weakness developed. Few cases in the literature have reported features of autonomic failure before established weakness in GBS; to our knowledge, syncope has not been described previously as a presenting feature of GBS.