Introduction: Devic’s neuromyelitis optica is an autoimmune and central nervous system demyelinating disease. It mainly affects the spinal chord and optic nerves. Considered for a long time as a special form of Multiple Sclerosis (MS), it is distinguished clinically by its rarity and poor prognostic, biologically by NMO (IgG) antibody, radiologically by extended myelitis. Treatment include mega dose of methylprednisolone during relapses and immunosuppressive drug in prevention of recurrences. Observation: Devic’s disease manifests itself in outbreaks of neuritis optic or myelitis. We report the case of a patient who had no particular antecedents. She presented a spastic tetraparesis, accompanied by a decreasing left visual acuity (4/10th);the all evolving by thrust since one year. Spinal chord lesions on MRI, second stage brain damages appearance affecting the white substance and the discovery in the patient serum of anti-aquaporin 4 antibodies (anti-AQP4 Ab) allowed the diagnosis of Devic’s disease. Conclusion: Diagnosis of Devic’s neuromyelitis optica that was initially based on clinical examination and radiological assessment is currently confirmed by the discovery in the patient serum of the NMO immunoglobulin G directed against Aquaporin 4.