Guillain—Barre syndrome (GBS) is the most common and severe acute paralytic polyradiculoneuropathy. Since its initial description by Guillain, Barre and Strohl in the year 1916 there has been a huge expansion in the knowledge of this potentially treatable disorder. 2016 marks the centenary year of GBS. It was conventionally described as an acute onset ascending pure motor demyelinating illness with areflexia. It has an annual incidence of 1/1000,000 across several studies. It can occur at any age with a slight male preponderance and with seasonal variations. However with ever growing knowledge in last 100 years the clinical spectrum under this umbrella has also expanded and several subtypes based on histopathology and neurophysiology have emerged. The various forms of GBS are Acute Inflammatory Demyelinating Polyneuropathy (AIDP), Acute Motor Axonal Neuropathy (AMAN), Acute Motor and Sensory Axonal Neuropathy (AMSAN), Miller Fisher Syndrome(MFS). AIDP is the more common in the western world while AMAN is more common in Asian subcontienent (in Japan and China). Other variants like pandysautonomia, pure ataxic GBS, pharyngeal- cervical-brachial GBS, bibrachial onset GBS and isolated bulbar palsy have also been described. Few cases may have retained reflexes, positive babinski sign, papilloedema and transient bladder involvement. Read more. . .