A 54 year-old woman showed the unusual association of a Guillain-Barré syndrome and opsoclonus, a rare eye movement characterized by involuntary bursts of jerking, ataxic and multidirectional saccades, without an intersaccadic interval. Since opsoclonus is a phenomenon described exclusively in CNS diseases, the case reported supports the hypothesis of CNS involvement in some cases of Guillain-Barré syndrome. The latter is generally considered an immune-mediated disease and an immune pathogenesis is also supposed in opsoclonus associated with systemic malignancies; besides, in the patient reported, the self-limiting nature of the disturbance and the lack of MRI lesions suggest that opsoclonus may result from an immune-related phenomenon causing a functional and transitory dysfunction of the CNS.