Multiple system atrophy (MSA) is a neurodegenerative disease characterized by progressive neuronal loss and alpha-synuclein deposition in oligodendroglial cells in the central nervous system. The cause of MSA remains essentially unknown. A cerebellar syndrome was associated with autoimmune thyroid disease in some cases, apparently not related to MSA and was partially responsive to immunomodulatory therapy.28 euthyroid patients who fulfilled the diagnostic criteria for probable MSA, 11 with MSA-cerebellar type (MSA-C), 17 with MSA-parkinsonian type (MSA-P), 28 patients with Parkinson's disease (PD) and 26 normal euthyroid controls were tested the for serum levels of anti-thyroperoxidase antibodies (anti-TPO) and anti-thyroglobulin (Anti-TG) antibodies (Ab).The laboratory results were statistically similar in all three groups, but 3 MSA-C patients had highly elevated anti-TPO Ab titers.We identified the presence of elevated anti-TPO levels in a small subgroup of MSA-C patients but neither in MSA-P or PD patients nor in healthy controls. These findings may suggest an autoimmune etiology in some cases of MSA-C.