The brain is often thought of as an immune-privilege site, implying that trafficking of immune cells and molecules into the central nervous system is limited or controlled so as to prevent collateral damage. Nevertheless, there is increasing evidence demonstrating complex interactions between the immune system and the nervous systems. The increasing evidence for the role of auto-immunity to neuronal proteins in both peripheral and central nervous system disorders has led to the development of animal models and in vitro systems to probe human disorders. This book reviews evidence for auto-immunity to neurons and axons in neurological diseases, discusses the animal models that are used to study the mechanisms of disease and indicates how such auto-immunity is relevant for therapies in these disorders