AbstractNeurofilaments are one of the major components of the neuronal cytoskeleton and are responsible for maintaining the calibre of axons. They are modified by post‐translational changes that are regulated in complex fashions including by the interaction with neighbouring glial cells. Neurofilament accumulations are seen in several neurological diseases and neurofilament mutations have now been associated with Charcot‐Marie‐Tooth disease, Parkinson's disease and amyotrophic lateral sclerosis. In this review, we discuss the structure, normal function and molecular pathology of neurofilaments. BioEssays 25:346–355, 2003. © 2003 Wiley Periodicals, Inc.