A cavernous angioma of the cerebellum occurred in a 55-year-old female presenting with a 3-year history of slowly progressive cerebellar signs and symptoms. Computed tomography and magnetic resonance imaging revealed a lesion in the left cerebellar nuclei and atrophic change of the affected cerebellar hemisphere. The final diagnosis was made at operation. The cerebellar nuclei and white matter were probably affected by the slowly expanding lesion, with repeated hemorrhage leading to degeneration of the afferent and efferent fibers, and subsequent atrophy of the affected cerebellar hemisphere.