Nine cases of Friedreich's ataxia and seven cases of autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) were submitted to neuroradiological procedures to determine the extent of atrophic processes in the central nervous system. All cases had a computerized cerebral tomography and five were studied with pneumoencephalography. The results show a correlation between the two tests and the comparison between Friedreich's ataxia and ARSACS. In Friedreich's ataxia, the radiological signs are variable and discrete in most of the cases. In ARSACS there are constant signs of cerebellar atrophy almost limited to the superior parts of the vermis and anterior lobes.