The molecular mechanism for ataxias has been elucidated in past 20 years. However, still it has not been developed a effective drug which prevents the disease progression or improves their symptom. One of the reasons for that is that the scales for ataxias, which we are using, are not suitable for clinical trial. The number of participant and the duration for a clinical trial is determined by the sensitivity and stability of scale to evaluate the efficacy the therapeutic methods. The available scale for ataxias needs more than 100 participants to evaluation the efficacy in more than 80% power. In addition, most of the scales for ataxias are a categorized scale, which is less sensitive and stable than a continuous scale. For success for clinical trial, we have to develop a new continuous scale for ataxias. In this symposium, we will learn the recent advance of physiological role of cerebellum and imagine a new continuous scale for evaluation for ataxias.