A previously unrecognized sequelum of infection with Campylobacter jejuni, a common cause of gastroenteritis, is Guillain-Barré syndrome (GBS). GBS is the most common cause of acute neuromuscular paralysis; 30% to 40% of cases are preceded by C. jejuni infection. Both patient and bacterial characteristics likely play a role in the pathogenesis of C. jejuni-induced GBS. Molecular mimicry between the LPS of some campylobacters and structures present on the gangliosides of the peripheral nerve may explain how this acute infectious diarrheal illness triggers GBS.