Exosomes, as a kind of extracellular vesicles generated by inward budding of the endosomes to form multi-vesicular bodies (MVBs), are secreted into the extracellular milieu and the systemic circulation thereafter. By endocytosis, direct fusion or receptor-ligand interactions, exosomes can interact with receptor cells and involve in various pathophysiological processes. Accumulating evidence have indicated that exosomes may play crucial roles in the pathogenesis of many neurodegenerative diseases including Parkinson's disease (PD), Huntington's disease (HD), Alzheimer disease (AD) and amyotrophic lateral sclerosis (ALS). In this paper, the roles of exosomes in the pathogenesis, diagnosis and treatment of PD and ALS are reviewed.