In pathologies such as progressive ataxias, clinical criteria are often not enough to provide the correct diagnosis. Therefore, we studied by means of MRI 30 normal volunteers and 19 patients affected by different progressive ataxias, diagnosed by typical standards. On all the subjects measurements were performed in order to identify normal and pathological ranges. Our experience confirms that typical involvement can be detected in the different kinds of progressive ataxias. Peculiar compromissions were found in spinocerebellar diseases, able to differentiate them from the forms mostly involving the cerebellum and brainstem. The differentiation between typical Friedreich and non-Friedreich diseases can also be suggested in most cases.