A case of Marinesco-Sjögren syndrome, displaying the characteristic signs (ataxia, congenital cataract and mental retardation) is presented. Electrophysiological examination pointed to the presence of a sensorimotor peripheral neuropathy with an underlying mixed process of segmental demyelination and axonal degeneration (probably secondary). The sural nerve and gastrocnemius biopsy confirmed these data, showing that in this case the segmental demyelination process was accompanied by axonal degeneration.