Aim: To define the sensitivity and speciality of cerebral-orbital MRI in diagnosing retrobulbar optic neuritis. Methods: Cross sectional descriptive study on the patients with cerebral-orbital MRI from 3/2009 to 3/2010 with and or without retrobulbar optic neuritis. The authors use a 1.5 - Tela - MRI machine to have axial and coronal images, the thickness of one section is 3 mm, 2 imaging doctors confirm the results. The authors concern about contrast enhancement sign on T1-weight, high signal foci on T2 - weighted. Results: study on 103 eyes of 85 patients including 23 males and 62 females. Mean age is 39.73 + or - 12.37. 20 patients without optic neuritis is used as control. Cerebro-orbital MRI is indicated. The gathered data is as follow: the sensitivity is 78.64 percent, the speciality is 75 percent, positive predictive value is 94.19 percent, negative predictive value is 59.46 percent, LR(+) 3.146, LR(-) 0.285. Conclusions: Cerebral-orbital MRI is totally believable in diagnosing retrobulbar optic neuritis.