Our understanding of the pathogenesis of cerebellar ataxias has started several decades ago and is continuously growing. The numerous mechanisms of cerebellar dysfunction are being discovered by numerous groups of researchers worldwide. Neuronal damage results from a complex interaction of metabolic pathways, which leads to symptoms observed in cerebellar disorders. The main mechanisms at the molecular level are the following: impairment of DNA repair and replication, deregulation of transcription/deficits of processing/transport of RNA, abnormal protein transport and misfolding, aggregates both at the nuclear and cytosolic level, activation of caspases, apoptosis, involvement of autophagic mechanisms, oxidative stress and mitochondrial dysfunction, excitotoxicity, abnormal lipid metabolism, impaired axonal transport and vesicle trafficking, and defects of the neurotransmission. The convergence of the current clinical classification with molecular findings is expected. This integration is a basic substrate for the rationale development of therapies.