Cerebellar ataxia is a syndrome characterized by gait instability, loss of coordination, and oculomotor and speech abnormalities. These diseases are highly heterogeneous both clinically and genetically. More than 200 causal genes have been described and different techniques are required for analyzing the various types of mutations: dynamic expansions, point mutations, or copy number variations. The use of new massive parallel gene sequencing techniques in recent years has exponentially increased our knowledge of the molecular bases of ataxias. It has allowed for the identification of new causal genes and has redefined the phenotypic spectrum of known genes. Nevertheless, in order to interpret the pathogenicity of the variants identified, taking a detailed family history and the phenotype of patients continue to be fundamental. This update will review the clinical manifestations of the most common forms and the most appropriate diagnostic strategy in routine clinical practice.