Behçet's disease is a multisystemic vascularitis of still unknown etiopathogeny. Among 400 cases of Behçet disease, 148 cases presented an optic nerve involvement during a period of eight years (1992-1999). The goal of this work is to contribute to the study of optic nerve involvement in Behçet's disease. The involvement is higher in males (64%) with median age of 27 years. The involvement of the optic nerve is noticed in 37% of cases. It's isolated in 7% of cases and occurs on average after 5 years of evolution of the disease. The diagnosis is based on the clinical examination, visual field, visual evoked potentials, retinal angiography and neuro-imaging (TDM and/or MRI). It can be an acute anterior neuropathy, stasis papilledema complicating a benign intracranial hypertension, neuroretinitis or retrobulbar optic neuropathy. The extraocular systemic manifestations were dominated by oral aphthosis (94%), genital aphthosis (70%), joint manifestations (40%) and central nervous system involvement (32.4%). The prognosis is reserved, 44% of patients having vision lower than 1/10 in spite of treatment. The authors insist on the therapeutic emergency that this involvement represents and the interest to consider it in all patients having an unexplained visual loss.