A 36-year-old woman was admitted to our hospital because of walking disturbance and dizziness. Her neurological examination showed psychiatric disturbance, truncal and limb ataxia, wide-based gait. She has taken 3 g of bromvalerylurea daily. The laboratory test revealed elevated levels of serum chloride (201 mEq/L) and bromide (105 mg/dl), and decreased (-43 mEq/L) anion gap. Brain MRI revealed atrophy of upper part of the vermis and cerebellar hemisphere, and widening of the primary fissure and dilatation of the forth ventricle. Bromvalerylurea, which is an easily available sedative, should be still noted as a cause of cerebellar ataxia. Increased level of serum chloride was useful information for early diagnosis of chronic bromide intoxication.