The authors describe here the ultrastructural findings in peripheral nerve biopsies from two affected members of a family with a previously undescribed intermediate form of Charcot-Marie-Tooth (CMT) disease. We found prevalent demyelinating features such as onion bulbs and myelin splits with uncompacted and irregularly enlarged lamellae, mostly at the Schmidt-Lantermann incisures and in paranodal region. Signs of a chronic axonopathy such as regeneration clusters, large fiber loss, Büngner's bands and unmyelinated fiber involvement were also seen. The presence of both demyelinating and axonal findings, not found in other genetically determined types of CMT disease, confirms the hypothesis of a new nosographic entity of intermediate type.