Here we describe the case of a 29-year-old woman, 36 weeks pregnant, with severe Guillain-Barré syndrome who delivered by Caesarean section because of respiratory insufficiency. The detection of high antibody titers to glycolipids of human peripheral nerve myelin in both the mother and the newborn, as well as differences regarding lymphocyte typing and levels of complement components, give rise to some reflections on the immunopathogenesis of this disorder supporting the hypothesis that cell-mediated immunity is the major mechanism in the development of Guillain-Barré syndrome.