Davidenokow's syndrome has been defined as a hereditary disorder characterized by proximal muscle weakness and wasting in the uper limbs with distal weakness in the lower, and associated with distal sensory loss in all four limbs. It has been assumed to be genetically distinct. A family is described in which the index case displayed these features. Motor nerve conduction velocity was substantially reduced. Another member displayed distal motor and sensory involvement in both upper and lower limbs and thus conformed to the clinical pattern of the hypertrophic form of Charcot-Marie-Tooth disease (hereditary motor and sensory neuropathy type I). A third member was somewhat intermediate, with generalized upper limb and distal lower limb weakness. It is concluded that Davidenkow's syndrome is not genetically distinct and that it may occur as a phenotypic manifestation of type I hereditary motor and sensory neuropathy.