Autoimmune mechanisms insult the cerebellum, resulting in the development of cerebellar ataxias (CAs). These immune-mediated cerebellar ataxias (IMCAs) include gluten ataxia, postinfectious cerebellitis, paraneoplastic cerebellar degeneration (PCD), antiglutamate decarboxylase 65 antibody-associated CA (anti-GAD ataxia), and primary autoimmune cerebellar ataxia (PACA). Cell-mediated mechanisms are assumed to be involved in PCD, whereas accumulating evidence shows that anti-GAD antibodies decrease the amount of GABA released which leads to functional synaptic deficits. The therapeutic benefits of immunotherapies vary depending on the etiology of the disease. Early intervention is recommended while the cerebellar reserve can be preserved.