Four cases of familial spastic paraplegia with amyotrophy in siblings from a consanguineous married are reported. The routine laboratory examination were normal. The electromiography and muscle biopsy processed by histochemistry showed signs of denervation with reinervation. The motor nerve conduction velocity was decreased in the peroneal nerve in 3 cases. The teased fiber preparation of sural nerves was abnormal in four cases. It was found increased of C, D and G fibers suggesting demyelination with secondary remyelination. The authors believe the abnormalities found could be due the distal axonal degeneration, with secondary regeneration and suggest the hypothesis that the fact is an axoplasmic flow defect in the central and peripheral nervous system.