Ataxia is a non-specific clinical condition resulting from a dysfunction of neural structures responsible for coordination of movements, for example the cerebellum causing cerebellar ataxia. Cerebellar disorders can be divided into the more frequent sporadic forms and usually rare inherited diseases. Inherited ataxias include autosomal recessive cerebellar ataxias, autosomal dominant cerebellar ataxias and episodic ataxias, and X-linked ataxias. Friedreich's ataxia (FRDA) is the most common of the genetically inherited ataxias with autosomal recessive transmission. Autosomal dominant spinocerebellar ataxias (SCAs) are a heterogeneous group of progressive neurodegenerative disorders, caused by diverse mutation types and complex pathogenesis, and clinically mainly characterized by cerebellar ataxia, resulting in unsteady gait, clumsiness, and dysarthria. The polyglutamine expansion SCAs share a mutational mechanism with other polyglutamine expansion diseases, such as Huntington's disease and spinal bulbar muscular atrophy. The most neuroimaging data are available for the subtypes SCA1, SCA2, SCA3, SCA6, and SCA17.