Charcot-Marie-Tooth (CMT) diseases constitute a clinically and genetically heterogeneous group of motor and sensory neuropathies. The current classification of CMT is based on the mode of inheritance and electrophysiological criteria, and whenever possible, on the responsible gene. This chapter provides an overview of the different forms of CMT and some practical guidelines on the diagnostic approach. The dominant forms of CMT are the most frequent in Western populations. Autosomal dominant forms are either demyelinating (CMT1), intermediate, or axonal (CMT2). Pedigrees with a proven autosomal recessive form of CMT account for only 4% of the families in CMT population. In demyelinating CMT, systematic screening, first for the 17p11.2 duplication and second for the GJB1 gene mutation, enables a molecular diagnosis to be made in about 70% of patients. Genetic counseling remains highly problematic in isolated patients with CMT.