In the past decade, a great progress has been made in understanding genetic basis of the spinocerebellar ataxia. Based upon the genotypes, more then 20 subgroups of autosomal dominant spinocerebellar ataxia have been identified with different gene mutations. Neither the pathomechanism nor the function of these genes is fully understood. In these disorders the main clinical sign is ataxia. Other symptoms may be present as well, but no specific clinical feature is known for differentiating subgroups. Specific diagnosis can be made by genetic tests. In this review we summarize the clinical features and genetic backgrounds of the most common spinocerebellar ataxias.