The present protocol is aimed at verifying the safety and efficacy of riluzole administration for a longer period, in a larger sample size of patients, with more stringent diagnostic criteria (hereditary cerebellar ataxia), respect to the above pilot study. Sixty patients will be enrolled in a double-blind, placebo-controlled trial. By central randomisation, patients will take 50 mg of riluzole or placebo twice daily for 12 months. Treatment effects will be assessed by comparing the Scale for the Assessment and Rating of Ataxia (SARA) before treatment and during therapy at months 3 and 12.