Knowledge concerning Guillain-Barré syndrome (GBS) has been largely extended these past ten years. The first description by Guillain, Barre and Strohl in 1916 established the main clinical and biological characteristics of the syndrome: acute motor weakness affecting at least one limb associated with areflexia. The syndrome was at first restricted to the concept of an acute inflammatory demyelinating polyneuropathy after the first large electrophysiological and histological studies (Asbury et al., 1969). This restricted definition of the GBS was changed by the report of Feasby in 1986 of an axonal variant of the syndrome. This proposal remained controversial until large studies reported that GBS in Northern China occurs in epidemics, predominantly involving young adults and children and characterized electrophysiologically by pure motor axonal features (AMAN). Additional studies showed that another GBS variant may result from an attack against both motor and sensory axons (AMSAN). Previously in 1956 CM Fisher described a clinical triad of ataxia, areflexia and ophthalmoplegia associated with albumino-cytologic dissociation and excellent recovery which was considered immediately part of the GBS. The physiopathology of the syndrome was recently determined (anti-GQ1b antibodies). A number of clinical variant of more limited scope have also been described. Plasma exchanges and intravenous immunoglobulin (IVIg) are the gold standard therapies for the demyelinating form and probably for the other variants despite the absence of controlled trials.