BACKGROUND: Bickerstaff's encephalitis (BE) is an acute post-infectious demyelinating disease with albuminocytological dissociation. A chronic form has rarely been described previously. CASE PRESENTATION: A 44-year-old man was hospitalized for drowsiness, cognitive complaint limb weakness, ataxia and sensory disturbance after diarrhea. Neuropsychological evaluation showed slowing, memory and executive function impairment, while analysis of the CSF showed albuminocytological dissociation. Immunologic tests showed positive anti-ganglioside antibodies (anti-GM1 IgM, anti-GD1a IgG and anti-GD1b IgM). Brain MRI was normal but SPECT showed bilateral temporal and frontal hypoperfusion. Outcome under immunoglobulin treatment (IVIG) was favorable with an initial improvement but was marked by worsening after a few weeks. Consequently, the patient was treated with IVIG every 2 months due to the recurrence of symptoms after 6 weeks. CONCLUSION: This case raises the question of the existence of a chronic form of BE with cognitive impairment, in the same way as chronic inflammatory demyelinating polyneuropathy is considered to be a chronic form of Guillain-Barré syndrome.