A 69-year-old woman developed subacute cerebellar ataxia and tremors in all four limbs in April 1996. Laboratory examination showed elevated antibodies against Ro and La. Head magnetic resonance imaging showed T 2 high-intensity lesions in the cerebellar white matter bilaterally and later in the pons. In April 2000, she died of multiple organ failure with incidental colon cancer. The autopsy showed atrophic parotid glands with an accumulation of lymphocytes around the ducts, confirming the diagnosis of Sjögren's syndrome histopathologically. The neuropathological examination revealed severe necrotic lesions in the cerebellar white matter bilaterally with several foci of perivenous demyelination in the periphery of the lesions and similar demyelinated areas in the pons. Immunohistochemistry with anti-JC virus antibody demonstrated no positive inclusions. A single focus of granulomatous arteritis was observed in one subarachnoid artery. The combination of Sjögren's syndrome, granulomatous angitis, and foci of perivenous demyelination suggests that an autoimmune mechanism played an important role in causing the necrotic lesions in the cerebellar white matter in this case.