Over the past decade, remarkable progress has been made in our understanding of the pathogenesis of Miller Fisher syndrome (MFS), a clinical variant of Guillain Barré syndrome (GBS). MFS comprises the clinical triad of ataxia, areflexia and ophthalmoplegia. It is associated with acute-phase IgG antibodies to GQ1b and GT1a gangliosides in over 90% of cases which are highly disease specific. Like GBS, MFS is a post-infectious syndrome following diverse infections, but particular attention has been paid to its association with Campylobacter jejuni enteritis. Serostrains of C. jejuni isolated from infected patients bear ganglioside-like epitopes in their lipopolysaccharide core oligosaccharides, which elicit humoral immune responses exhibiting molecular mimicry with GQ1b/GT1a gangliosides. These antibodies are believed to be the principal cause of the syndrome and physiological studies aimed at proving this have focused on the motor-nerve terminal as a potential site of pathogenic action. This review describes these findings and formulates a pathogenesis model based on our current state of knowledge.