The spinocerebellar ataxias (SCAs) are a clinically, genetically, and neuropathologically heterogeneous group of neurological disorders defined by variable degrees of cerebellar ataxia often accompanied by additional cerebellar and non-cerebellar symptoms that, in many cases,defy differentiation based on clinical characterisation alone. The clinical symptoms are triggered by neurodegeneration of the cerebellum and its relay connexions. The current identification of at least 43 SCA subtypes and the causative molecular defects in 27 of them refine the clinical diagnosis,provide molecular testing of at risk, a/pre-symptomatic, prenatal or pre-implantation and facilitate genetic counselling. The recent discovery of new causative SCA genes along with the respective scientific advances is uncovering high complexity and altered molecular pathways involved in the mechanisms by which the mutant gene products cause pathogenesis. Fortunately, the intensive ongoing clinical and neurogenetic research together with the applied molecular approaches is sure to yield scientific advances that will be translated into developing effective treatments for the spinocerebellar ataxias and other similar neurological conditions.