AIM: To report a case of unilateral optic neuritis with multiple sclerosis in an Asian child. METHODS: A case report. RESULTS: A 10-year-old Chinese girl presented with history of sudden loss of vision of the right eye for 3 days’ duration. It was associated with pain in eye movement. She gave history of fever associated with ataxic gait a year ago. She had been diagnosed to have acute disseminated encephalomyelitis (ADEM). Visual acuity in the right eye was 'counting finger' with positive afferent pupillary defect. The optic disc was swollen and hyperemic. The colour vision was severely impaired. Visual field showed central scotoma and enlarged blind spot. Magnetic resonance imaging (MRI) of the brain revealed multiple intense lesions in the left occipital lobe, basal ganglia and periventricular regions suggesting multiple sclerosis. She was treated with intravenous methylprednisolone for 3 days, followed by oral prednisolone for 11 days. She had excellent recovery and her visual acuity improved to 6/9. She remained asymptomatic for 3 years. CONCLUSION: The simultaneous occurrence of optic neuritis and multiple sclerosis is less common in children and seldom reported. We presented this case to highlight the possibility of this disease occurring in Asian population in a younger age group.