Charcot-Marie-Tooth (CMT) <<disease>> is the generic name given to a group of genetic disorders characterized by a relatively isolated dysfunction of peripheral nerves, with combined motor and sensory impairment. These CMT syndromes are the most frequent genetically-determined peripheral neuropathies, with a global prevalence between 4.7 and 36/100,000. Their clinical phenotype is predominantly motor, with a grossly symmetrical distal amyotrophy involving both lower and upper limbs. Mode of inheritance is variable: autosomal dominant, autosomal recessive or X-linked. Apparently sporadic forms can be a difficult diagnosis and they must be considered in all patients with a chronic polyneuropathy which is not clearly of acquired origin. During the last two decades, the identification of more than 25 genes mutated in CMT syndromes has complicated the classification of these disorders. Knowledge of the function of some of these genes has improved our understanding of the pathogenesis of myelinic or axonal dysfunction in CMT, but for some others their function remains elusive or unknown.