A 54-year-old female developed dysarthria, left limb ataxia, and crossed dissociated sensory impairment, followed by external ophthalmoplegia, severe bulbar palsy and bilateral pyramidal tract involvement. A high titer of anti-GQ1b IgG antibody was detected in her serum. Brain MRI (T2 weighted image, diffusion weighted image) and peripheral nerve conduction study were normal. We diagnosed her as having Bickerstaff's brainstem encephalitis. In the past literature, we could not find any case of Bickerstaff's brainstem encephalitis showing crossed dissociated sensory impairment.