Introduction: Osmotic demyelination syndrome is a rare medical condition in which parkinsonian signs are relatively non frequent. Objective: To report a case of a patient with hyponatremia rapidly corrected and treated with neuroleptics. The cranial MRI showed demyelinating lesions in pons and basal ganglia. The patient clinically developed parkinsonism, with no response to dopamine. Conclusion: The inadequate correction of hyponatremia causes demyelinating lesions. As we appreciate in this case, the prescription of neuroleptic drugs may negatively affect the response to dopaminergic therapy.