In order to characterize the electrodiagnostic features of autosomal-recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) more fully, we report the clinical and neurophysiological findings in two patients from a Spanish pedigree with a homozygous missense point mutation in the SACS gene. Nerve conduction studies showed signs of both axonal and demyelinating neuropathy. In the upper-limb nerves, motor conduction velocity was intermediately slowed. Sensory nerve action potentials were attenuated or absent. In addition, slowed conduction in the central motor, somatosensory, and auditory brainstem pathways was observed, and masseter and blink reflexes were abnormal. As a whole, this constellation of electrophysiological findings helps in the diagnosis of ARSACS.