This presentation discusses the immunobiology of the Guillain Barré syndromes (GBS), the world's leading cause of acute autoimmune neuromuscular paralysis. By gaining an understanding of the clinical and pathophysiological pathways operating in GBS, we can hope to develop novel immunotherapies that will improve clinical outcome. Here we focus on GBS mediated by anti‐ganglioside antibodies and highlight the correlations between anti‐ganglioside antibody patterns and clinical phenotypes, the development of models of GBS, and the application of novel therapies based on inhibition of complement activation.