Hereditary neuropathies (HMSN) are among the most common genetic diseases in neurology. Various mutations in different genes are known which lead to the most frequent hereditary neuropathies. These mutations concern proteins of the myelin of the peripheral nervous system, as well as a gap-junction protein expressed in peripheral nerves. The molecular mechanisms leading from gene mutation to disease phenotypes are not fully understood. Nowadays, we are able to use DNA analysis for symptomatic, presymptomatic, and prenatal screening. The latter is of questionable value because of the variability in disease severity and outcome. Deeper insights into the molecular pathophysiology will, however, yield new therapeutic strategies in individual patients.