A large kinship is reported with dominantly inherited spastic paraplegia starting in the first decade of life; its clinical evolution was indistinguishable from that of "pure" hereditary spastic paraplegia (HSP). However, all patients studied had electrophysiological evidence of a predominantly sensory polyneuropathy, which was confirmed on nerve biopsy in three. The histological findings indicated virtually complete loss of large diameter fibres with relative preservation of small myelinated and non-myelinated fibres. The neuropathy was largely asymptomatic and there were no trophic ulcers. This family represents a distinct entity which differs from other reported cases of HSP with neuropathy by virtue of the clinical predominance of the pyramidal syndrome, the greater impairment of large fibre sensory modalities than of pain or temperature modalities, and the consequent absence of mutilation.